I have KDX200s and I tried the ATF type F, thats the only one you want to use. Dont use the Dextron or any of the others. It shifted great but I was worried it was too thin. Ive heard of guys mixing the two. I had No problems what so ever using it. The bike maker specs 10w30. I ussually use 15w40 just for the shear protection. Tell you the truth when you are talking about the gearbox on a two stroke dirtbike they are so tough and so simple, I am pretty much thinking you could dump Cooking oil in there and it would work. Tried 75w90 gear oil, didnt work at all. Grabbed terribly. Dont try that. If you want to try the ATF, try it, it wont hurt anything, just make sure you use the type F. Its supposed to have more lubricacy.