what to do after car oil has been used?

My friend just picked up a used 250 ninja(yeah i know) and we are thinking maybe the previous owner used car oil. The clutch slips a bit and it may or may not be caused by the use of car oil. Now would the use of synthetic bike oil be good because the detergents might clean the clutch or would it be screwed anyway? Like i said we dont know for sure about the car oil but im just curious. Put regular kawi oil in it today and it seems to be better

Many wet clutches don't work well with energy conserving oils (car or motorcycle) that have additives such as Molly. First change the oil and filter and use the type oil recommended for the bike. Synthetics are fine but I don't know if you would see the real benefit in that bike so it's probably spending money you don't have to. If there is a way to adjust the clutch go ahead and check the adjustment then ride it for awhile because if the oil is the cause it will take a little time before you see a big difference from the oil change.

I agree with HOG SLYR, although the smaller cc (250 and less) sportbike engines are hardest on oil, so even though your motor will probably require periodic rebuilds anyway, a good synthetic oil will extend the rebuild interval. If you aren't going to keep that bike long, it's probably not worth the money. If you are, it probably is, if the motor is otherwise still in good shape.

Money on the fact it's a learner bike being why the clutch slips rather than the oil used. You can't know until you take it apart but, I bet you find burnt/worn clutch components in there. When you find no/little wear and the clutch still slipped, that's how it looks when EC oils have been used. Nothing wrong with car oil that's non-EC in that application. K7

synthetic