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Does anyone know if there is any difference in motorcycle engine-oil and car engine-oil?

or dear god please dont tell me you put car oil in your bike!
yes there is a large difference!

Big difference. Car oils will make your clutch slip.

Thank for the heads up. I didn't know.

I have always used car oils in my bikes and always will. I have never noticed any ill effects. In fact it is pretty rare for any of the auto shops I frequent to have anything motorbike specific (other than 2 stroke oil).

Is it a different situation in the US?

Those of you screaming "huge difference" please tell me why Shell Rotella is so popular amongst motorcyclists.

I'm running oil meant for heavy duty diesel TRUCKS. Works fantastic.

There are certain car oils with additives in them that will make the wet clutch of a motorcycle slip. However, there is a lot of debate on this issue. Just do a google search of car oil vs. motorcycle oil and you can read for days.

Some car oils may work just fine, but some won't. I like to play it safe. I only run Mobil 1 Racing 4T in my bikes.

The amount of shear force the oil takes is most of it. Auto engine oil does not have the additives to account for the shear force the gears in the transmission will put on the oil, in fact auto engine oil is not recommended for any transmission use. The heavy oil used for diesels like Rotella will.
I have used auto oil before, years ago, the stuff will break done real fast in a bike engine due to the transmission, I did not have trouble with the clutch slipping though. There were some tests showing how fast car oil broke down in bike engines compared to bike oil, it lasted like a 1/3 as long, after 1000-1200 miles it was broke down as if it had 5000-6000 miles on it.

In the U.S. if the oil is marked "energy conserving" on the label. you shouldn't use it in your bike, it contains friction modifiers (clutch will slip).
Other conventional car oils not marked as energy conserving will work in a bike with a wet clutch or unit transmission but it is likely the shearing action of transmission gears will reduce the life of the oil.
If you use a good quality car oil and change it frequently, you should be ok.

I agree completely. The actual differences between motorcycle oil and its automotive counterparts may be considerably less than we have been lead to believe. The link below is to an article regarding motorcycle oil vs. automotive oils and the the viscosity-retention question.

http://www.nightrider.com/biketech/oiltest1.htm

Quote from the test:

Bottom Line
It could appear from this data, then, that there is no validity to the constantly-used argument that motorcycle-specific oils provide superior lubrication to automotive oils when used in a motorcycle. If the viscosity drop is the only criterion, then there is certainly no reason to spend the extra money on oil specifically designed for motorcycles. There does, however, appear to be a legitimate argument for using synthetic and synthetic-blend oils over the petroleum based products.


So thats why i felt ripped-off after paying 48 euro's for 4 litres of motorcycle oil.

So synthetic non-energyconserving is the best i guess

jimcarson,

Good oil test link you posted...
I have used both car oils and bike oils over the years and frankly have never seen a difference.
Never had an oil related failure in any bike.
I live in Florida (HOT) and even with air cooled bikes the car oil (Castrol GTX or Valvoline) were fine.
I do change my oil and filter between 2500 and 3000 miles.

Gentlemen: Check out BobIsTheOilGuy.com. Lots and lots of ACCURATE information by engineers, fleet managers, and others who really know their stuff (as opposed to "everybody knows...) There's a separate forum for bikes, and another for actual used oil analysis.

a good read here