ok here's the down low on this bike, Rcannon has the exact same model so he is your go to guy for anything, I have a 98 Yz 250 that is the same engine. I'm sure you already have found out that the fill hole for the tranny is directly under the exhaust pipe, if you can't get it off with your fingers then use a pair of pliers, to fill the engine with oil, a little trick I use is to get a large syringe. The kind used for pets. And keep filling the syringe and injecting it into the hole. Put a whole 750ml into it no matter what the oil level check hole says. Because of that I am not going to tell you where the oil level check bolt is, you'll never find it. Have fun, and you were a little confused with the engine oil thing. Two strokes use oil in their transmissions to lubricate the gears and the clutch. the oil you put in the gas lubricates the cylinder and the crank as well. But they do use oil.
Jeff