What is the difference between car oil and motorbike oil?

Note that motorbike oil may be different from car oil because in some motorbikes, the oil is also used to lubricate the disc type clutch. For this reason, most automotive oils are too slippery because of special additives and should not be used where a disc clutch is involved. Using an oil formulated for automobile engines can, and usually will, cause the motorbike disc clutch to fail on bikes and atv's. Some oils, like some of the 15w40 weight oils formulated for diesel engines only, will perform correctly in disc clutches on bikes.