DT Yamahas ALL have a wet clutch - don't use car oil in the engine, nor any oil that does not specifically say that it is for motorbikes. If the oil has any "friction modifiers" in it, then they will coat the clutch plates and you'll get clutch slip. If you have already done it (hence the question) then you will need to warm up the engine, drain out the oil and dispose of it with care, then re-fill with the correct oil. If the clutch still slips after a few miles , then repeat the full process but use a flushing oil to clean out the wrong oil from the clutch plates. then drain and re-fill with the right stuff.
Helpful Mark, October 2008
