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2K views 18 replies 10 participants last post by  alias 
#1 ·
Hi all

I have searched the forum but can't find an answer to my query.

I have a '99 SLR650 which I intend to give regular oil changes, however motorcycle specific oil is much more expensive than car oil. I have always used car oil in my BMWs and British bikes but have read dire warnings of clutch slip if car oil is used with a wet clutch.

Please someone tell me the truth and let me know what oil will suit my SLR!

Ian
 
#2 ·
My view is based on the fact that motorcycle (and car) manufactures go to great lengths to specify the appropriate oil for their products. They outsource testing to specialist third parties at some considerable cost. On the basis that they go to this trouble, and then provide a specification that allows you to buy any make of oil with that correct specification ( so no real opportunity for income generation for them) I chose to stick to oil of the correct spec. It's not that much difference in price and if components last longer and the bike runs smoother then costs may well be less!
I always use the correct oil.
 
#3 ·
I am pretty sure Bobn uses car oil he buys it by the 40liter drum and changes it every 1000 miles in his slr's . you will get people saying don't use car oil it ruins the clutch I used to use car oil myself years ago and I never had a clutch go on any bike . but I bowed down to peer pressure and now only use oil with a illustration of a bike on the gallon .maybe clutches go on bikes ridden by people who cant ride too good or maybe too good at the traffic light drag strip or the previous owners ?
 
#4 · (Edited)
Why use car oil, look around & proper bike oil can be had at a good price, when you see it on offer stock up.
Eg, Hein Gerike recently had 4ltr of semi synth for £12 for 4ltrs, I tend to go for Smith & Allan (Darlington) semi synth at under £14 for 5ltr with a farcebook discount code.
It seems daft using oil of the incorrect spec to maybe save a couple of quid.
 
#7 ·
Apart from any clutch issue with wet clutches.
Its the Gearbox too.
If you do not not have seperate gearbox (eg 650 Honda singles) then the oil has the engine and gearbox duties.
Cars tend to have seperate gearboxes with different oils.
I would not run a car with gearbox oil in the engine or engine oil in the gearbox...its the shear qualities required for gears.

I have bikes with dry and wet clutches, seperate gearboxes and integrtaed (unit) engines...different oils used in them.
 
#8 ·
I think the wet clutch slipping issue is more to do with whether the oil is partly or fully synthetic, rather than whether it is intended for cars or bikes. There are some threads on here about clutches slipping with fully synthetic bike oil.

Having said that, I'd agree with the previous comments about oils designed for specific purposes, particularly the high shear and pressure forces in gearboxes. The oil quality and changing frequency probably have a greater effect on engine life than any other single factor, so if you won't pay for the best oil, what's the point in doing all the other things properly? As Mr Shandydrinker says, choose the best oil and pay as little as you can for it.
 
#11 ·
Don't use car oil.
I used to use it, but when the spec went from SG to SL they started including friction reducing additives and these will knacker your clutch. Now I buy 10W40 JASO MA2 in bulk 40 litre drums.
JASO MA2 is the latest spec for motorcycles.
 
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#12 ·
Why is my clutch not damaged? I've never bought bike specific oils and so far as I can tell from the specs shear for bikes and cars isn't much different.
What does appear different are the friction modifiers, moly or PTFE which appears to matter go clutches, not mine perhaps but maybe some of yours.

The EU have been pushing lower friction in engines for a while it seems.
 
#13 · (Edited)
Well, you're correct - the anti friction additives cause clutch slip on wet clutch engines. If yours is fine then you've got away with it (for now).
Regarding shear etc. yes an engine is an engine is an engine, but bike engines have integrated gearboxes which chop up the long chain polymers and all the crud thrown off as the clutch wears in normal use shouldn't be encouraged to find its way to the top end, so motorcycle oils tend to have lower detergent content too.

Factor in that I'm fortunate enough to live 5 miles from an oil company that will sell me 25 litres of 10W40 JASO MA2 semi-synth for £37 and it's a no-brainer for me....
 
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#15 ·
Haha! I've been accused of far worse than that :thumbup:
 
#16 ·
This thread reminded me, I bought the same 10/40 jaso ma2 from Aztec oils as bobn, and was surprised to find it is coloured red. Sunday morning (with a drained frame and sump) couldn't find a thing on the net about red dye in oil - when I was in the trade years ago the only red oil was ATF. A quick call to Aztec Monday morning who confirmed, yes we colour it red to differentiate it from our 20/50 motorcycle oil. Well there you go!
 
#17 ·
S'good stuff! Hope that Vigor's still making you smile!
 
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