The good oil...on oil

[Pump]

Here is a good site which answers a few questions about which oil. Well worth a read.

http://www.sportrider.com/tech/146_0308_oil/index.html

I use silkolene pro 4 15/40

 

[PsychoXJR]

Good site that theres a guide to suspension on there aswell that is well worth a look.

[Stray]

All right folks, I have rattled off an email to the R&D department at Silkolene and finally got a reply a few weeks later. I hope this settles a lot of the conflicting info available out there regarding oil advice, and helps riders make informed decisions about which oil to put in their XJRs.

The email conversation is cut-and-pasted below, starting with the questions I asked, and ending with the answers received from John Rowland at Silkolene's R&D department:

Stray

From: Stray
Question: Hello,
 
Is your Comp 4 10W-40 oil good for wet clutches in air-cooled
motorcycles? The manufacturer (Yamaha XJR 1200) recommends a
semi-synthetic oil, but the Comp 4 reads "synthetic" on the label.
 
Also, our Owner's Group has been arguing for many years about the use of
synthetic v semi-synthetic oil in "old style" air cooled bikes with a
wet clutch.
 
The argument centers around the following:
1) Air cooled bikes have higher tolerances than water cooled;
2) Wet clutch presents a dilemma between the need for high lubrication
in the motor, and the need for friction in the clutch. These are
opposing requirements from the same oil;
3) Air cooled bikes get VERY hot in traffic, and so a stable oil is
needed that will not degrade, but this is traditionally the speciality
of fully synthetic oils, which are thought to be unsuitable for these
motorcycles (particularly the wet clutch).
4) Finally, I am not sure whether riders should switch from one grade of
oil to another as the bike gets older (high mileage).
 
Any help is appreciated, and I would really like to lay these arguments
to rest with the opinion of a qualified person. At the moment we seem to
get different answers depending on who we speak to, so a proper
professional opinion would be great.
 
Thanks and regards,
 
Stray

Dear Stray,
            Yes, the Comp-4 grades give excellent clutch performance in
air-cooled bikes. Comp-4 oils are actually semi-synthetic:
ester/hydrocracked/mineral. (But, contrary to popular belief, this has
nothing to do with clutch performance. There great deal of false
information circulating among bike enthusiasts. See attachments.)
 
Questions!
1)...so use the shear-stable C'4 20W/50. Very popular oil for large A/C
classics here in the UK, and in hot climates such as Croatia.
 
2)Not so 'opposing' as many people think. Metal-to-metal friction is not
the same as fibre + resin friction to metal. Simplistic wear/friction
tests (the Americans like them!) are very misleading.
 
3)True, but the RIGHT semi-syn can be very heat resistant. (Any comment
about 'synthetic' is meaningless unless the TYPE od synthetic is
specified.)
The Comp oils have a good record. Our Pro-4+ 10W/50 is extremely heat
resistant, and gives excellent clutch traction. It can be done.
 
4)No problem changing grades or mixing oils. Another internet myth.
 
Yours sincerely, John Rowland (R & D dept.)  Happy reading!!
 

As you can see, the man seems to know what he is talking about, even if he did not quite answer question 4. Nevertheless, it suggests that the Pro 4 oil (a FULLY synthetic oil) might be suitable for the XJR, as it gives the dual advantage of "excellent clutch traction" and "extreme heat resistan[ce]". What do you guys think? Is it time to upgrade to fully synth oil?

John sent me some attachments which I will cut and paste into separate postings. There are 4 of them in total, and they cover just about EVERYTHING you want to know about oil. Mr Administrator, Sir, please let me know if I have overstepped the posting allowance, so I can remove these posts if required.

Personally, I have just purchased some semi-synthetic 10-40 which I don't want to throw away, but perhaps the next oil change will see some fully synthetic oil in the old sump. I might even go with a 10-30 oil, as the XJR operates at 80 degrees celcius when warm, and that would make the viscosity perfect at the hotter end. The only concern is that 10-30 has poor shear resistance (possibly countered by esters in the fully-synth?), so more frequent oil changes are required.

Then I will be able to tell you all how well the clutch engages and whether there are any problems (if there are, I can just drain the oil again and fill up with semi-synth). That will have to wait about 2k miles though, so be patient.

Has anyone else thrown in a semi-synthetic? What is your experience?

Best regards,

Stray

 

[Stray]

This is a discussion John (Silkolene R&D) had with a chap about why Castrol was a bit crap in his R6, whilst the same grade Valvoline was better...


Dear Mark & Dave,
 
                            Any statement which roughly fits into this
category: 'fully synthetic/semi-synthetic oil must not be used in the
Kawasuki Hellfire ZZX because it will cause.... (whatever)' is TOTALLY
MEANINGLESS unless the TYPE OF SYNTHETIC IS DEFINED. And I don't care
who says it. This must be the thousandth time I've said this, so I'll
say it again. 'Any advice about 'synthetic' lubricants is complete
nonsense unless the type of synthetic is stated.' Some so-called
synthetics for example are physically and chemically so close to mineral
oil as to be almost indistinguishable, where others may look oily but
they're totally different chemically. (See attached. Sorry, it was
originally written for Subaru drivers.)
 
     The JASO MA series of tests are a Good Thing, but the clutch
friction test they use is very easy to pass, so much so that JASO have
tightened the limits in their updated JASO MA2 tests. (JASO MA is NOT
just a clutch test.) Even so, I'm not keen on the method they use, which
was originally designed to test ATF, and based on a car clutch. So one
JASO MA (or MA2) oil can be better than another from a clutch friction
point of view. Now I could be biased, but a clutch friction test which
uses modern motorcycle clutch parts seems a better idea to me; and it
just happens that for the past four years I've been running friction
tests on motorcycle oils using sections of m/c clutch plates! I could go
into a lot of detail (you have been warned) but four factors have come
out as significant:
 
1)       Low viscosity grades generally give better friction
coefficients at low temperatures. (Pretty obvious. The oil gets out of
the gap quicker.)
 
2)       Temperature is very important. Not just because hotter means
thinner; in fact, friction often goes down with higher temps (I test up
to 230C) especially with non-M/C blends.
 
3)       At the high temperatures found in clutch packs in competition
use, by far the most important factor is the activation temperature of
the standard anti-wear compounds used in all engine oils.
 
And finally.......
 
4)       The type and amount (ie 'semi-' or 'full') of synthetic base
oil, or mineral oil, has absolutely nothing to do with clutch friction.
 
 
 
Yes, the whole business of synthetics and clutch friction is a complete
red herring.
 
 
 
So what happened with your R6? It could have been a good JASO MA oil
versus a marginal one, but my guess is that the Valvoline was acting as
a thin oil, even though it may have been 10W/40 on the can. Decent motor
oils of European origin always have better shear stability than USA
grades, so in high shear situations such as gear teeth or dog clutch
faces, the Castrol was probably acting at a higher viscosity.
 
 
 
                                                     Yours sincerely,
 
 
John Rowland, (R & D Dept.)
 
 
 
  _____  
 
From: deleted
Sent: 04 March 2008 21:10
To: deleted, John
Cc: Pryde, Kenny
Subject: RE: Oil
 
 
 
Hi John,
 
We've had the following email from a reader (below).
 
Now, I have to admit, I can't remember exactly what we said about the
use of fully-synths in the feature. What do you make of his comments?
 
Thanks in advance-
 
David.
 
 
 
 
 
 
  _____  
 
Date: Tue, 4 Mar 2008 09:42:38 +0000
Subject: FW: Oil
From: deleted
To: deleted
 
/??
------ Forwarded Message
From: deleted
Date: Tue, 4 Mar 2008 09:10:27 +0000 (GMT)
To: deleted
Subject: Oil
 
Morning Kenny,
 
 
 
The other month in your mag you did a special section on oil, your chap
was saying that any fully synthetic oil is ok for bikes providing it had
JASO on the container. I did an oil and filter change on my 2007 R6
track bike last week and used it at Donington on Saturday, the oil I put
in was Castrol Power 1 fully synthetic 10w 40 JASO and all that, I
thought I was doing the bike a favour, instead, all day the bike seemed
to have trouble selecting gears up and down the box, more up than down.
Up until that point I was using Valvoline synthetic blend and the bike
was fine, what have I done wrong??...
 
 
 
Also, please understand I'm not saying that your chap doesn't know what
he's talking about, but I have asked Suzuki if I can use a fully
Synthetic oil in my GSX-R1000 K5 track bike, they say "absolutely not,
it will damage the clutch or parts of it"...Who the hell is right
here!!!???..
 
 
 
Regards, Mark.
 
 
Regards, Mark deleted
 
------ End of Forwarded Message

[Stray]

This is a discussion John (Silkolene R&D) had with an author of a Superbike magazine. It gives some good knowlegde about how oil works and what is best for your bike...

Dave:
     OK! First instalment! I'm off tomorrow; I'll have another bash Mon.
 
1)How is an oil manufactured; transformed from the black sludge that
comes out of the ground, into the nectar-like substance we pour into our
bikes?
 
Crude oil, which is usually very thin, (contrary to popular belief!) is
distilled into light and heavy fractions, with several intermediate
ones. (The evil left-overs are used to fuel the 15 million cc/40RPM
diesels in the giant oil tankers that bring the crude to the refinery.)
The lighter fractions, usually more than 90% of the original crude, are
converted into petrol and diesel. Some of the heavier oils, (still dark
and smelly!) go through several processes to clean them up and remove
wax. Out of about a dozen oily products 4 clear, bright amber oils are
commonly used to blend modern engine and gear oils. These are roughly
equivalent to SAE 10, 20, and 30 engine rating and 140 gear rating. Oil
refineries also produce all sorts of gases and chemical compounds which
can be used to build up 'tailor made' lubricants: synthetics! Read on.  
 
2)What are the most important substances added to the refined base oils?
What do they do?
 
In the Dark Ages bikes used blends of refined mineral oils 'straight',
with nothing added. The trouble was, even in the slow-revving engines of
80 years ago the oil didn't last very long, and the engines didn't
either. Black sludge and corrosion were the killers, and both were
tackled in the 1950s with detergent and antioxidant chemicals. (When I
was a lad, I used to visit a mate of me Dad's who rebuilt the very
popular side-valve Ford engines. The thick crap inside these things was
unbelievable! The valve tappets were moving in holes in solid blocks of
carbon!) The detergents washed the carbon from fuel combustion off the
bores and out of the ring grooves, and at the same time reduced bore and
piston ring corrosion. The antioxidants stopped the oil reacting with
oxygen in the air, which cut acid sludge formation which in turn reduced
corrosion and oilway blockages. Some antioxidants had the useful
side-effect of reducing wear as well. This added up to longer oil and
engine life, both improving about three times. (Straight oil had to be
changed every 1000miles, and even lightly-stressed engines running on it
were ready for a full overhaul at 15-20,000.) OK, I admit there were
design and metallurgical improvements, but they needed that vital
'liquid component' to be fully effective. Later came dispersant
compounds which held the carbon as tiny particles in the oil which
didn't settle out anywhere, and slipped through the oil filter as if it
wasn't there.(Solid bits in well-used modern oil are about 1/1000mm
across; the pores in an oil filter are at least 15 times bigger.)
    The other big problem with oil used to be cold starting. It was
usual to have SAE 20 Winter or 'W' grades, and SAE 30 or 40 Summer
grades, and even the so-called Winter types would defeat the starter in
serious cold weather. Unfortunately, oil is very thick when it's cold,
and very thin when it's hot. To have an oil thick enough to look after a
hard working engine, you had to use a grade which was too thick when it
was cold. The answer was (and is) multigrade! What was needed was an oil
that behaved like a 20 'W' grade in the cold, but only thinned down to a
SAE 40 or 50 when really hot; yes, 20W/50! This can be done by mixing
thin oil with thick polymers based on plastics and synthetic rubbers;
these don't do much in the cold, but as the oil warms up they unwind and
thicken it up to some extent. The oil still thins down, but not as
quickly as a polymer-free or monograde type. Multigrades started to
catch on around 1960, but these pioneer types were easily ruined by
mechanical shear effects, more so in gearboxes than engines. These days
the better quality polymers resist shear even in combined
engine/transmissions, so it is essential to use good quality
shear-resistant types in a motorcycle, which gives its oil a hard time
in both engine and gearbox.
     Incidentally, there are large amounts of these additives and
polymers in there, it's not just 'a little bit of this, a little bit of
that'! A good quality mineral 10W/40 can be 80% base 20% additive
chemistry, and guess which is the expensive ingredient!
 
3)What are the differences, in layman's terms, between mineral,
semi-synthetic and fully-synthetic engine oil ? (In terms of structure
and performance.)
 
Before we get into details, the first thing to realise that there is no
chalk and cheese difference between mineral and synthetic based oils.
After all, the chemical compounds which make mineral engine oils so much
better are themselves synthetic. Synthetic lubricant bases are stepwise
improvements on mineral oil, with more desirable properties and fewer
undesirable ones. The second important point is that there's no one
thing called 'synthetic'! There are several different types of synthetic
lubricant, and to say something like: 'the Supergrunt XXR must have a
full synthetic' is meaningless unless the 'expert' explains what sort of
synthetic he means. Equally, to imply that dreadful things will happen
if the 1970 Hardley-Ableson Bluegrass is run on anything other than
Pennsylvania mineral is ridiculous. It may not need a 2007 synthetic,
but it isn't going to come to any harm if the owner uses a 2007
synthetic.
   The most basic type of synthetic is really a special mineral oil.
Known as 'hydrocracked' bases, these are made in oil refineries by
putting certain types of mineral fraction through special processing, so
they cost more than the usual mineral types but not much more. They are
useful because they resist evaporation at high temperatures. Although
used for years for genuine technical reasons, they are now popular with
marketing men because the magic sexy word 'synthetic' can legitimately
be printed on the label without spending much on the oil inside the can!
Yes, all low-cost 'synthetics' contain anything from a few percent to 20
percent (i.e. 'semi-synthetic') of special mineral oil.
   Using fairly simple chemical compounds or gases from oil refineries
or other sources, it is possible to 'synthesise' or build up tailor-made
lubricant molecules which have very desirable characteristics, such as
great resistance to cold, heat, evaporation losses or excessive thinning
as they get hot. These are the true synthetics, and the two that are
used in engine oils are PAOs (poly alpha olefins) and esters. Neither is
cheap! PAOs are related to mineral oils, and are the ideal carriers for
all the chemical compounds used in mineral oils. Because they do not gel
at very low temperatures, all genuine 0W-something oils have to be based
on PAOs to pass the 0W test at a sub-arctic -35C. Esters were originally
made for jet engine lubricants, and to this day all jet oils are
ester-based. Although similar in performance to PAOs, they have a
valuable extra trick: they are good lubricants and help to protect metal
surfaces.
    As 0W- and 5W- grades are not usually recommended for motorcycles,
perhaps the best all-round oil is a 10W/40 shear-stable semi-synthetic
with some ester content. Esters help with transmission and valve train
lubrication. 100% fully-synthetic oils are actually quite rare, probably
because they are very expensive to make, and even more expensive to buy.
Even so, an ester/PAO with a very shear stable multigrade polymer is the
ultimate oil for high output engines that are worked hard, which means
racing.
 
4) How does oil work? What gives it its lubricating properties? How does
it 'cling on' to surfaces?
 
A plain bearing such as a main or big end, when spinning fast is
'floating' on a relatively thick film of oil. The metal surfaces
literally do not touch. The high velocity drives a wedge of oil between
the two surfaces, and the oil film supports the load, just like a water
skier skimming over that very thin lubricant, water. But, when the
engine slows down and stops the bearing shells drop through the film and
touch the crankpins, just as the skier sinks in up to his neck when he
lets go of the rope. It is where there is metal to metal contact that
lubrication, that is, something to reduce wear and seizure, is needed.
On gear teeth, valve components, and piston rings at top or bottom dead
centre, there is no high speed rotation to generate 'wedge' support, so
the oil films are very thin, and some metal contact is inevitable. Some
fluids, even if they look thick and oily, are completely hopeless! Very
pure mineral oils, and some synthetics fall into this group. They depend
entirely on chemical load-carrying compounds which react with metal at
high pressures and temperatures to provide very thin protective films
which prevent micro-welds where metal surfaces come into contact.
Detergent and antioxidant chemicals often double up as anti-wear agents.
The odd ones out are esters. These are attracted to metal by
electrostatic forces and cling on when surfaces are forced into contact.
 
 
5) What are (or can be) the main differences between oils of the same
type, i.e. what's the difference between a 'good' and a 'bad' oil?  
 
It all comes down to honesty really.....so beware!  A good oil is what
it claims to be on the can. 10W/40? Does it really pass the cold test at
-25C? Quite a few I've tested do not. There is usually an API spec
quoted, such as API SH or SL. These are car-based, but a good basic
quality guide. If absent, leave it on the shelf, and avoid lawyer-speak:
'meets the requirements of....' or 'recommended (by whom?) for use
in....'. The JASO MA or MA2 spec is a good sign, because this
Honda/Kawa/Yamaha/Suzuki-sponsored series of tests is entirely
motorcycle-orientated, and includes a clutch slip test, a
shear-stability test, and a high-temperature/high shear viscosity
minimum permitted level. The 'big four' were pushed into introducing
this series of tests back in the late 90s by the poor quality of
USA-produced oils.
   Then there is the 'synthetic' minefield! Provided the price hasn't
been pushed up by shipping an average oil 5000miles from the West coast
of the USA, you get what you pay for. The best motorcycle oils are made
in the more developed European countries, but low price buys the cheap
'modified mineral' synthetic and not much of it, with a poor multigrade
polymer. As is so often the case, quality follows cost.
 
What are the likely consequences of using poor-quality oil?
 
Usually, these are fairly long term, except in racing. Think of the oil
as a liquid component, and poor oil as a cheap pattern spare. In a
touring bike, long-term reliability and performance retention (i.e.
acceleration figures below new spec., fuel and oil consumption above)
are the casualties. Particularly in a high performance or racing bike,
the effects can be more immediate and catastrophic. I recently saw a
Honda CBR 600 crankcase/block from a racing sidecar. All 4 bores were
scored from top to bottom on the thrust sides, and all 4 pistons ruined,
needless to say. The whole casting had to be scrapped. After spending a
lot of cash on race preparation, the owner had saved a few quid by using
a cheap 10W/40'workshop' oil, probably API SG or lower, no JASO spec,
and the used oil had sheared down to SAE 30.
Now this is the really crazy part: it was the second engine he'd ruined
on the same oil!
 
                               JR
 
-----Original Message-----
From: deleted
Sent: 16 July 2007 12:31
To: deleted, John
Subject: SuperBike: Oils feature
 
 <<Oil questions.doc>>
 
Dear John,
 
Thanks for agreeing to help out with this feature - much appreciated.
 
I have attached a list of questions for your perusal. As I mentioned on
the phone, please try and make your answers as idiot-proof and concise
as possible... Bear in mind, I'll be restricted to about 1,000 words
total for the feature, which is an introduction/overview of oils, rather
than an in-depth technical analysis... so I think it's most important to
convey the key points in an accessible way.
 
Feel free to include anecdotes, such as your story about the chap with
the destroyed CBR motor. Also, feel free to add extra questions, if you
think it's necessary. Likewise, if you think any of my questions miss
the point in any way, feel free to adapt/ignore as necessary.
 
If you could get your answers to me by next Monday (23rd July), that
would be fantastic. Any problems or queries, don't hesitate to give me a
shout.
 
Many thanks in advance-
 
David.
 
David deleted.
(Staff Writer)
 
SuperBike Magazine

 
Direct Tel: deleted
 
Live the dream at www.deleted

 
 

[Stray]

More stuff about oil from John at Silkolene. Some of it is waffle about amphibious cars, but most of it is very interesting reading about oil...

Dave:   ....and so it goes on! Got back from an abortive trip to the
Prescott Hillclimb on Friday in the amphibious Morgan! Turned back half
way, in time to pick up a phone message that they'd 'pulled the plug on
it'. Well, at least the new waterproof trousers worked a treat....
 
 
 
Some oil companies have run advertising campaigns that imply their
products have special, unique qualities. Can these adverts be taken
seriously?
 
 
 
7) Yes and no! Generally adverts in motorcycle magazines* are honest,
with marketing-speak terms such as 'Magnatec' and 'Electrosyntec' really
being code words for esters, which are particularly beneficial in
motorcycle-orientated oils. No manufacturer has any unique 'secret', so
it's all down to providing the best possible blend for the job at the
right price, and making it clear that you get what you pay for. I
personally think that the importance of shear stability or 'stay in
grade' is not stressed enough.
 
What is dodgy is claiming that a mineral based oil with a few percent of
modified mineral ('hydrocracked') synthetic is the D.Bs and suitable for
racing, etc. when it clearly isn't. Also, there is endless semantic
manoeuvring and lawyer-speak around The Magic Word....'synthetic'. For
instance, a 'synthetic' oil is invariably semi-synthetic ('Ah!....we
didn't say it was all synthetic did we?), and, if low priced, invariably
the modified mineral type synthetic. It is a sad fact that you get what
you pay for, but even so, stick to the reputable UK/European brands, and
remember that shipping an oil half way around the world doesn't
automatically make it better than one made in your home town.
 
      (*As for TV advertising...well, does anybody believe it? Due to
its huge cost, a TV advertising campaign can significantly raise the
cost of specialist items such as oil. Everybody assumes it's just a few
pence per gallon, but it can be pounds per gallon.)
 
 
 
Please can you explain the grading system? What is meant by the weight
of an oil? What does 10W/40 mean for example?
 
 
 
Weight means viscosity, or resistance to flow. Water and paraffin
flow very easily, so they are low or light viscosity. Golden syrup or
140 gear oil do not come out of the can so easily, so they are high or
heavy viscosity. Especially with oils, temperature is very, very
important. An oil which looks 'heavy' at 20C will be very 'light' at
100C. People sometimes say, 'I drained the oil when the engine was hot
and it ran out like water...' so I say, 'Good! It's supposed to be like
that!' The American Society of Automotive Engineers (SAE) ratings cover
cold starts and 'up and running' viscosities. There are two sets of
standards, the 'Winter' (W) ratings, and the 100C standard ratings. ('W'
does not, repeat not, mean 'weight'!) So a 10W/40 oil has to pass a 10W
cold viscosity test at -25C, and a SAE 40 test at 100C. In an oil lab
there will be a refrigerated viscosity measuring device for the 'W'
tests and another at 100C for the standard SAE tests. There are 6 'W'
ratings from the difficult 0W at -35C to the dead easy 25W at -10C,
occasionally used in India for example! The whole point of these Winter
ratings is to assist cold starts, to get the oil circulating quickly,
and to avoid power and fuel wasting drag as the engine warms up. Once it
is warmed up, the 100C ratings count. There are 5 of these, 20, 30, 40,
50, and 60 although why anybody bothers with 60 in the 21st Century is a
mystery to me!
 
      Sorry folks, but I've got to get technical. Viscosity is measured
in standard units called 'Centistokes', names after a Victorian
engineer, Sir George Stokes, who used to time ball bearings as they sank
through oil. SAE 30 for example is from 9.3 to 12.5 Centistokes, and SAE
40 follows on at 12.5 to 16.3, although most SAE 40 oils are in the
middle at about 14. Now this is something most don't realise: engines do
not know what grade of oil they're running on. They're not clever
enough! So an engine filled with 10W/40 will be running on a viscosity
of 14 at 100C, but with a sump temperature of 90C its seeing a viscosity
of 18, so as far as the engine is concerned it's running on SAE 50.
Likewise, at 110C, it's down to 11 Centistokes so it 'thinks' it's on a
SAE 30! (Which is preferable.) The lesson is, do not use power and
fuel-wasting thick oils in cool climates. A decent 10W/40 or even
thinner is perfectly OK unless you're riding an air-cooled classic with
wide clearances and a slow oil pump.
 
      Radical race cars use 1300 Suzuki Hyabusas and work them very
hard. (Didn't one take the old Nurburgring absolute record recently?).
They use our high-ester 15W/50, but that's OK because they see oil temps
around 130C! (No problem for the oil or the engine, but they do fit
special oil seals.) At 130C the true viscosity is 10cSt, so the engine
thinks its on a thin SAE 30, which keeps it happy.
 
 
 
What is the best type of oil to use in a road bike for general riding?
Is fully synthetic a waste of money?
 
 
 
9) Personally I'd go for a shear-stable ester semi-synthetic, SAE 10W/40
or 10W/30. The 'shear-stable' bit (ie, a decent quality multigrade
polymer) is actually more important than the 'synthetic' part! If
strapped, I'd go for a shear-stable mineral based oil rather than a
'synthetic' of dubious stability that's probably based on modified
mineral oil anyway. Unless you're covering a huge annual mileage,
genuine 100% synthetics are probably an extravagance. High mileage
long-distance fans can use a light full synthetic and save on fuel and
oil changes, and cut overhaul costs if things get to that stage, but
more later.....
 
 
 
What are the main differences between 2 and 4-stroke oil? Why does
2-stroke oil have to be mixed with fuel?
 
 
 
10) 2-stroke oil has a very short working life, straight in and out, and
it gets burnt. The 2-stroke engine doesn't have a sump full of oil and
the bearings are all rollers, so there's hardly any oil drag, hence no
need for multigrades. Long term stability is obviously not a problem!
But, 2-stroke must burn off without leaving any plug-fouling or
detonation-initiating deposits. The detergent and anti-wear additives
used in 4-stroke oil leave hard white ash behind when they burn, just
what you do not need in a 2-stroke. So 2-stroke oils use low-ash
detergents and dispersants, and the better types use ester synthetics to
act as anti-wear compounds. With current environmental concerns, smoke
is a sensitive issue, so most 'road' 2-stroke oils are now low smoke,
which requires yet another type of synthetic base designed to burn off
invisibly. For some rather basic but very high-revving air-cooled racing
2-strokes there's still some sense in using blends with that marvellous
anti-seize liquid, castor oil!
 
  Due to crankcase induction and compression, the classical 2-stroke
obviously cannot have an oil-filled sump, so the only way to keep an oil
film on anything was to add oil to the fuel, or inject oil into the
crankcase space where it could mix with the fuel vapour. There are now
some engines where the fuel and oil are injected separately, but the oil
is still burnt.
 
 
 
How important is it to change oil regularly? What are the implications
of failing to do so?
 
 
 
11) It is only really important to change oil regularly if the bike
covers a low annual mileage made up of slow, short runs. This is being
cruel to the oil and the engine! The oil, regardless of its quality,
gets full of fuel and water vapour, and never gets the chance to
evaporate it all off with a long fast run. The consequences are
corrosion, ring and bore wear, and gear tooth pitting. It is essential
to do a change at least once a year, even if the recommended mileage
hasn't been covered. On the other hand, if you eat up the miles on long
blasts the engine and its oil will love it, so with a top-quality oil it
is OK to cheat a little on oil drain periods.
 
 
 
Do some types of oil (i.e. fully-synthetic) 'wear out' quicker than
others? How important are timely oil changes? Can you rely on the
frequency suggested by your bike's User Manual?
 
 
 
12) (Your enquirer has got it arse about face!)
 
The type of oil that is likely to give trouble after low mileage is a
light viscosity non-JASO MA type with poor shear stability, either
mineral or modified mineral based. (Such as one of the USA 'fuel
economy' oils for lazy car engines that pushed the Japanese OEMs to
bring in their own oil spec.) The important thing is the shear
stability; the much hyped 'synthetic or mineral' nonsense is a red
herring. The oils that will last the longest are the relatively rare
100% genuine synthetic shear stable types, which will easily stand twice
the recommended drain period in a high-mileage high performance bike.
(So in the long run they aren't really so expensive.) Just the thing for
those touring fiends who pack the panniers and set of for the
Transylvanian Alps as soon as the clocks go forward! (Fancy an oil
change in L'Viv?) Of course, User Manual drain recommendations are based
on a back-covering 'worst case' scenario of low annual mileage on poor
quality oil, so they can be regarded as a very safe minimum mileage.
 
          In the past, there used to be trouble with heavy carbon
deposits and sludge around the engine with early low-detergent oils, but
these days almost any oil with a good API specification will keep
everything clean for 10 to 15,000 miles, so that's the least of your
worries.
 
 
 
Does oil have to be warm to do its job properly? Is it important to warm
up your bike before riding at speed?
 
 
 
13) Yes, it does have to be at least warm, and preferably hot. Most
people except vertical twin riders with white finger syndrome find metal
at 60C too hot to touch, yet 60C is too cold for oil in an engine that's
going flat-out. The best approach is to use a good 10W/40 or even a
5W/40, and take it easy for the first couple of miles, especially in
very cold weather. For racing, a really good warm-up is essential,
except perhaps with special 0W/20 low-drag race oils. The trouble is,
oil pumps are very good at pushing oil out at 60PSI, but unfortunately
there is only 14PSI (atmospheric pressure) pushing it in! (Even less in
Katmandhu.) So it's easy for an oil pump to pull voids or pockets of
vacuum in the oil if it doesn't flow fast enough into to uptake. This
'cavitation' obviously reduces the amount of oil the pump can deliver.
Also, in high-speed bearings the oil can be too thick to keep up with
the high rubbing speeds reached in modern engines so the 'wedge' or
hydrodynamic' effect breaks down. I know it goes against common sense
(whatever that is) but the faster a bearing is turning the thinner the
oil should be.  (A 4cm. diameter main bearing is rubbing its shells at
56 MPH at 12,000RPM! To avoid cavitation the oil need to be less 10cSt
or less, which is SAE 30 if the oil happens to be at 100C, or SAE 40 if
its at 110C.))
 
 
 
What is the difference between road and racing oils?
 
 
 
14) The days of incense-like 'R' oils for racing only are past, except
for classics. At least as far as 4-strokes are concerned, the best
synthetic types are ideal for both race and road use. (Well, that's our
policy. All of our race oils are on the retail price list!) With
ultra-precise components, high-pressure pumps and high engine RPM there
has been a move to special synthetic low cavitation/low drag oils to
release more power with no reliability loss. These can be (and are!)
used in road bikes, but 0W/20 is not mentioned in the user handbooks, so
there is always some warranty risk.
 
 
 
How does a high-performance oil allow the motor to produce more power?
 
 
 
15) An engine wastes fuel energy in several ways, and most of them are
due to the laws of thermodynamics, which is another way of saying you
can't do much about it. But up to 6% of engine output is lost due to oil
drag, made up of pumping losses and viscous drag between moving
components. The transmission is included in this in most motorcycles.
Provided wear and friction are kept down, there are real gains to be
made by using a 'tough' but low viscosity oil. Surprisingly, frictional
losses are low, down at 3% or less even with conventional oils, so there
are few gains to be made here.
 
   I have actually seen this extra power output on the dyno! A very
experienced operator in Peterboro who does a lot of test work for Lord
Emap used his own year-old Honda Blackbird, with the first run on his
favourite 15W/50 high-ester synthetic. 128BHP. Then we changed to a 5W40
high ester synthetic. (So it wasn't an unfair comparison with B & Q
15W/50!) This time we saw 131.6BHP with a corresponding torque increase.
Finally we went to a new (at that time) 0W/20 special synthetic and
134.4BHP appeared! Even the boss was impressed! Later trials in
different race and road bikes showed this level of improvement was no
fluke, so it really does work; and, with the right chemistry to look
after the engine and transmission internals, there's no down side of
increased wear.
 
 
 
Why do some engines consume oil? Is this a problem?
 
 
 
16) Large air-cooled engines with wide piston clearances, or very highly
stressed liquid-cooled engines which flex under load, or which use
ultra-light pistons with the minimum number of rings are likely to be
oil users. There is little that can be done about it. Unfortunately,
burnt oil tends to leave hard deposits in the combustion chambers which
can initiate pre-ignition, so more frequent top overhauls are usually
necessary.
 
       Occasionally, touring engines will use oil for no apparent
reason. This is often due to the oil level rising in the crankcase due
to air retention, leading to oil loss through the breather. The answer
is to move to a lighter grade of oil to improve air release.
 
 
 
If you need to top up your engine oil, how important is it to use
exactly the same brand and type?
 
 
 
17) Not very important at all. Unfortunately, due to 'arse covering'
reasons we cannot print this advice on the can! Although officially all
manufacturers advise against mixing different makes and grades, in fact
there is very little chance of any harm being done, even if one is a
mineral 20W/50 and the other is a 5W/30 synthetic. Obviously, avoid this
if you can, but do not panic if there's no other alternative. Just don't
mix 2 stroke and 4-stroke oil!
 
 
 
There are all sorts of additives available which are supposed to improve
ordinary oil and reduce friction, improve power output etc. Are they
worth a try?
 
 
 
18) Oil is already a very advanced and deeply researched fluid which
does not need any 'enhancement'. There is no secret formula out in the
backwoods that the mainstream lubricant chemists do not know about; but
there are plenty of half-baked ideas and gullible people out there!
These wonder additives are usually 1930s chlorinated paraffins, long
obsolete gear oil additives which should have disappeared in the 1950s,
but they keep turning up as 'Xxtrasuperlube ZX3' with a mark-up of
several thousand percent.  They actually corrode engine and transmission
internals, so they do far more harm than good. Others depend upon the
total myth that PTFE powder coats engine internals and reduces friction.
It doesn't do anything or the sort. It just blocks the oil filter. The
AA tested one of these overpriced PTFE concoctions ('Quick 60' or
something) very thoroughly back in the 80s. They stated: 'This is an
expensive way of coating your oil filter'.
 
 
 
                                                                   Aurevoir,  JR

[Stray]

This is the final installment from John at Silkolene. It is a reply to a Subaru owner, but then it goes into wet clutches and motorcycles. Very useful...

Lubricating the Subaru    (........or any modern high-performance engine; but this was originally written for the Subaru Owners’ Mag.)

Basically

Basically, to use that irritating in-word, engine lubrication is simple, and consequently boring.  So I intend to treat the subject ‘complicatedly’, which may not be an in-word, but makes life far more interesting!

So, to take a quick look at the simple picture; the oil keeps moving parts apart, reducing friction and carrying away heat.  Where there is metal-to-metal contact there are chemicals in the oil to reduce the damage.  Because the internal combustion process is always less than perfect, some soot is produced and this must be washed off the pistons and rings by the oil, so it has a cleaning or detergent function.

The trouble is, all this is just as true for Henry Ford’s original Model T engine as it is for the Subaru or any other high output motor.  So where is the difference?  The Model T, with 10BHP / litre at 2,000 revs per minute and a single underhead camshaft, was filled with a thick, greenish liquid from somewhere near the bottom of the distillation columns on the Pennsylvania oilfields.  It did a vague tour of the internals by guesswork (there was no oil pump) at a temperature around 50 C, and lasted for 1,000 miles.  On the plus side, some of the impurities acted as anti-wear and detergent chemicals.  They didn’t work very well, but it was better than nothing.  The engine wore out in around 20,000 miles, but even ordinary people, not just amateur rally drivers, were happy to put up with this.

The difference begins with the first turn of the key.  The modern high-pressure pump would cavitate on the old heavy monogrades, starving the bearings for a vital couple of seconds, even in warm weather.  Likewise, cam lobes would suffer as the sluggish oil found its way along narrow oil ways to the valve gear.  The turbo bearing (‘if fitted’, as the handbooks say) already spinning fast, would also starve, and when it got going, how long would it be before the heat soak-back fried the primitive oil into a lump of carbon?  (This was a problem even with ‘modern’ oils only 15 years ago.)

So, a good oil must be quite low in viscosity even in the cold, so that it gets around the engine in a fraction of a second on start-up.  On the other hand, it must protect engine components (piston rings for example) at temperatures up to 300 C without evaporating or carbonising, and maintain oil pressure.

Unmodified thin oils simply can’t manage this balancing act.  The answer is to use a mixture of thin oil and temperature-sensitive polymer, so as the thin oil gets even thinner with increasing temperatures as the engine warms up, the polymer expands and fights back, keeping the viscosity at a reasonable level to hold oil pressure and film thickness on the bearings.  This is called a multigrade.

But this is all too basic!  What I have just written was and is relevant to a 1958 Morris Minor.

The questions that Subaru owners need to ask are: “Will this thin base oil evaporate and be drawn into the intake manifold (via the closed circuit crankcase ventilation), leading to combustion chamber deposits and de-activated catalysts?” and “Will the polymer shear down at high engine revolutions and high temperatures, causing low oil pressure and component wear?”  and “Will it carbonise on the turbo bearing?”  These are 21st century questions which cannot be answered by a basic 1990’s approach.

BUT!  Before we head into more complications, some figures…

The SAE Business (American Society of Automotive Engineers)

Viscosity is the force required to shear the oil at a certain speed and temperature.  Oils work because they have viscosity; the drag of a rotating part pulls oil from a low-pressure area into a high pressure area and ‘floats’ the surfaces apart.  This is called hydrodynamic lubrication, and crank bearings depend on it.  In fact, a plain bearing running properly shows literally no metal-to-metal contact.  Experimental set-ups have shown that electrical current will not flow from a crank main bearing to the shells.  Also, the energy loss due to friction (the co-efficient of friction) is incredibly low, around 0.001.  So for every kilogram pulling one way, friction fights back with one gram.  This is very much better than any ‘dry’ situation.  For example, the much over-rated plastic PTFE has a co-efficient of friction on steel of 0.1, 100 times worse than ‘ordinary’ oil.

Oil viscosities are accurately measured in units called ‘Centistokes’ at exactly 100 C.  These fall into five high temperature SAE categories:-

(< means ‘less than’)

SAE No.   20   30   40   50   60
Viscosity range   5.6 - <9.3   9.3 - <12.5   12.5 - <16.3   16.3 - <21.9   21.9 - <26


A decent quality oil usually has a viscosity that falls in the middle of the spec, so a SAE 40 will be about 14 Centistoke units, but SAE ratings are quite wide, so it’s possible for one 40 oil to be noticeably thicker or thinner than another.

When the polymer modified multigrades appeared, a low temperature range of tests were brought in, called ‘W’ for Winter (no, it doesn’t mean Weight!).  These simulate cold starts at different non-ferrous monkey endangering temperatures from -15º C for the 20W test to a desperate -35º C for zeroW (0W).  So, for example, a SAE 5W/40 oil is one that has a viscosity of less than 6600 units at –30º C, and a viscosity of about 14 units at 100º C.  Now, those who have been paying attention will say “Just a minute!  I thought you said these multigrade polymers stopped the oil thinning down, but 6600 to 14 looks like a lot of thinning to me!”  Good point, but the oil does flow enough to allow a marginal start at –30º, and 14 is plenty of viscosity when the engine is running normally.  (A lot more could damage the engine.  Nobody uses the 24 viscosity SAE 60 oils any more.)  The vital point is, a monograde 40 would be just like a wax candle at –30º C, and not much better at –10º C.  It would even give the starter motor a fairly difficult time at zero.  (At 0º C, a 5W/40 has a viscosity of 800 but the mono 40 is up at 3200.)

Another basic point about wide range multigrades such as 5W/40 or 0W/30 is that they save fuel at cruising speeds, and release more power at full throttle.  But complications arise…

Building a good oil

A cave may not be the best place to live, but it’s ready-made and cheap.  This is the estate agent’s equivalent of an old-style monograde oil.  Or you could get Hengist Pod to fit a window and a door; this is moving up to a cheap ‘n’ cheerful mineral 20W/50.  But an architect-designed ‘machine for living in’, built up brick by brick, is an allegory of a high performance synthetic oil

It is impossible to make a good 5W/40, or even 10W/40, using only mineral oil.  The base oil is so thin, it just evaporates away at the high temperatures found in a powerful engine that is being used seriously.  Although there are chemical compounds in there to prevent oil breakdown by oxygen in the atmosphere (oxidation) they cannot adequately protect vulnerable mineral oil at the 130º C plus sump temperatures found in hard worked turbocharged or re-mapped engines.

Synthetics are the answer.  They are built up from simple chemical units, brick by brick so to speak; to make an architect-designed oil with properties to suit the modern engine. 

But sometimes, if you look behind the façade, there is a murky old cave at the back!  This is because the marketing men have been meddling.

The Synthetic Myth

What do we mean by the word ‘synthetic’?  Once, it meant the ‘brick by brick’ chemical building of a designer oil, but the waters have been muddied by a court case that took place in the USA a few years ago, where the right to call heavily-modified mineral oil ‘synthetic’, was won.  This was the answer to the ad-man’s dream; the chance to use that sexy word ‘synthetic’ on the can… without spending much extra on the contents!  Most lower-cost ‘synthetic ‘ or ‘semi-synthetic’ oils use these ‘hydro-cracked’ mineral oils.  They do have some advantages, particularly in commercial diesel lubricants, but their value in performance engines is marginal.

True synthetics are expensive (about 6 times more than top quality mineral types).  Looked at non-basically, there are three broad categories, each containing dozens of types and viscosity grades:-

1)   PIB’s (Polyisobutanes)
These are occasionally used as thickeners in motor oils and gear oils, but their main application is to suppress smoke in 2-strokes.

The two important ones are:-

2)   Esters
All jet engines are lubricated with synthetic esters, and have been for 50 years, but these expensive fluids only started to appear in petrol engine oils about 20 years ago.  Thanks to their aviation origins, the types suitable for lubricants (esters also appear in perfumes; they are different!) work well from –50º C to 200º C, and they have a useful extra trick.  Due to their structure, ester molecules are ‘polar’; they stick to metal surfaces using electrostatic forces.  This means that a protective layer is there at all times, even during that crucial start-up period.  This helps to protect cams, gears, piston rings and valve train components, where lubrication is ‘boundary’ rather than ‘hydrodynamic’, i.e. a very thin non pressure-fed film has to hold the surfaces apart.  Even crank bearings benefit at starts, stops, or when extreme shock loads upset the hydrodynamic film.  (Are you listening, all you rally drivers and off-road fanatics?)

3)   Synthetic Hydrocarbons or PAO’s (Poly Alpha Olefins)
These are, in effect, very precisely made equivalents to the most desirable mineral oil molecules.  As with esters, they work very well at low temperatures, and equally well when the heat is on, if protected by anti-oxidants.  The difference is, they are inert, and not polar.  In fact, on their own they are hopeless ‘boundary’ lubricants, with less load carrying ability than mineral oil.  They depend entirely on the correct chemical enhancements.

In fact PAOs work best in combination with esters.  The esters assist load carrying, reduce friction, and cut down seal drag and wear, whilst the PAOs act as solvents for the multigrade polymers and a large assortment of special compounds that act as dispersants, detergents, anti-wear and anti-oxidant agents, and foam suppressants.  Both are very good at resisting high-temperature evaporation, and the esters in particular will never carbonise in turbo bearings even when provoked by anti-lag systems.

Must Have MORE Power!

Motorcars are bought for all sorts of reasons, but enthusiasts like lots of power.  To get power, a lot of fuel must be burnt, and more than half of it, sadly, gets thrown away as waste heat.  For every litre of fuel burnt, 60% of the energy goes as waste heat into the exhaust and cooling system.  A turbocharger can extract a few percent as useful energy and convert it into pressure on the intake side, but only 40-45% is left, and only 25-odd percent actually shows up as B.H.P. at the flywheel.  6% goes in pumping air into the engine, 6% as oil drag losses and 2 or 3% as engine friction.  The oil deals with at least 97% of the friction; so reducing the remaining few percent is not easy.  If you doubt that even an ordinary oil has this massive effect, take a clean, dry 200 BHP engine, connect it to a dyno and start it up.  It will only make 1 BHP for a few seconds.  Now that’s real friction for you! 

Oddly enough, people get starry-eyed about reducing friction, especially those half-wits who peddle silly ’magic additives’, which have not the smallest effect on friction but rapidly corrode bearings and wallet contents.  In fact, even a virtually impossible 50% reduction in the remaining engine friction would be no big deal, perhaps one or two BHP or a couple of extra miles per gallon.

Even More Power!

The place to look for extra power is in that 6% lost as oil drag.  In a well-designed modern motor, the oil doesn’t have to cover up for wide clearances, poor oil pump capacity or flexy crankshafts, so it can be quite thin.  How thin?  Well, take a look at these dyno results.

A few months ago we ran three Silkolene performance oils in a Honda Blackbird motorcycle.  This fearsome device is fitted with a light, compact, naturally aspirated 1100c.c. engine which turns out 120+ BHP at the back wheel.  The normal fill for this one-year-old engine was Silkolene Pro-R 15W/50, so the first reading was taken using a fresh sump-full of this grade.  (The dyno was set up for EEC horsepower, i.e. pessimistic.)

Pro-R 15W/50
Max power   127.9 BHP @9750 rpm
Torque      75.8 ft-lbs @ 7300 rpm

 
After a flush-out and fill-up with Pro S 5W/40 the reading were;
Pro S 5W/40
Max power   131.6 BHP @ 9750 rpm
Torque      77.7 ft-lbs @ 7400 rpm

Then we tried a new experimental grade, Pro R 0W/20, yes, 0W/20.  This wasn’t as risky as you may think, because this grade had already done a season’s racing with the Kawasaki World Superbike team, giving them some useful extra power with no reliability problems.  (But it must be said, they were only interested in 200 frantic miles before the engines went back to Japan.)

Pro R 0W/20
Max power   134.4 BHP @ 9750 rpm
Torque      78.9 ft-lbs @ 7400 rpm

In other words, 3.7 BHP/2.9% increase from GTI to Pro S, a 2.8 BHP / 2.1% increase from Pro S to Pro R, or 6.5 BHP / 5% overall.  Not bad, just for changing the oil, eh?  More to the point, a keen bike owner would have paid at least £1000 to see less improvement than this using the conventional approach of exhaust / intake mods, ignition re-mapping etc.

Am I recommending 0W/20 for Subarus?  Well, perhaps not!  The Pro S 5W/40, which is a ‘proper’ PAO/ester shear-stable synthetic, will look after a powerful engine better than a heavier viscosity ‘cave at the back’ conventional oil, and provide a useful few extra BHP.  (On the other hand, the 0W/20 was very thoroughly developed to give good anti-wear protection.  I think I was on ‘Blend 6’ before Kawasaki was happy with it!) 


The End……


However, as with all good things in life, we don’t live a perfect world of perfect motorcars and therefore we have to look at the lubrication trade-off between longevity, reliability, power, and cost, relative to the vehicle in which the oil is being used (a scruffy Fester XR2i with 193,000 miles on the clock is a very different proposition to your spanking new Impreza).   Which is why Subaru (and probably your local dealer) recommends a 10W/50 (such as Pro S 10W/50); you could look at a 5W/40 for competition and Track-day use, but only the most committed competitor would want, or need, the 0W/20 Pro R for the extra 5% power.

So… perhaps there is a Subaru Hill-climber, sprinter or rally type out there who is willing to take a punt on the 0W/20 in the never-ending quest for power?  Could be interesting.


John Rowland
R & D Automotive Chemist at Fuchs Lubricants (UK) plc, who make Silkolene oils.
(Under pressure, admits to falling off anything on 2 wheels, so drives a Morgan 3-wheeler instead, or a 43 year-old Mk 1 Sprite for luxury travel, with such decadent refinements as doors, synchromesh, and hydraulic brakes.)

[GregXJR]

Hi Stray

Just a thought, if the emails were sent to you in confidence then perhaps best to take out the third party email addresses etc. I'm sure Silkolene won't mind you publishing their response, particularly as you comment favourably.

Cheers

Greg

[Stray]

Greg, you are spot on about the 3rd party email addresses - don't know how that one got past me.

I've deleted them all, I think, but if you spot any more, please let me know.

Stray