Hey everyone, I'm relatively new to dirtbikes and just bought an 09 yz250f, when I first tried it I found it had alot of low end power, then when I took it home and changed the oil I noticed a difference. I had used SAE10w40 car oil, unaware that there was oil specific to motorcycles. I had only gone on one ride, maybe an hour long with that oil and I swapped it out immediately after realizing what I had done. I just want to know if putting that oil in there would cause the bike to pull less even though I swapped it out quickly. I realize that part of the problem could be that I'm more used to the bike and the power, but even on a grippy surface like pavement it doesn't pop up as easily to me. I used a kimpex filter, I assume it makes no difference but I figured I should throw that in there. This is my first post, so try to be gentle. Thanks in advance! Edit: I forgot to mention that when I changed the oil I discovered that both of the threaded holes on the oil tank are stripped, I plan on re-tapping them one size up before going out and buying a new one. after tapping, to remove any excess oil residue that may contain metal shavings in the tank, what type of degreser should I use to wash it out? I don't want to use something that will leave a film and then effect the new oil that I put in. Thanks again. Edited May 12, 2011 by UltimatePunch Forgot some information.