You're not suppose to use any synthetic oil in your new 250 F engine or gearbox. It says so right in your owner's manual.
You know.....I certainly didn't mean to start a controversy over what choice of oil you should be using, and I most definitely did not intend to spread MISINFORMATION on this forum. I re-read my owner's manual, and it states "do not add any chemical additives or use oils with a grade of CD of higher." I thought a CD rating meant it was synthetic. If not , I stand corrected.
Moreover, just to prove a point, I called all four of the Yamaha Dealership's here in town this morning, and asked to talk to the Service Manager. Guess what all four of them said when asked about synthetic oil for the WR 250 F.....you guessed it....all four of them recommended against using synthetic oil...all four of them expressing fears of clutch and gear slippage.
I stand by what I originally posted. It's just my opinion. It makes no difference to me what kind of oil you want to use. Just remember, if you do try using a full synthetic, and you do find your clutch slipping, it's next to impossible to completely drain all the synthetic oil out.
It's slippery stuff, and coats itself to the internal parts of your gearbox, leaving you with the same problem once drained and replaced.
[This message has been edited by ^SQUID^ RACING (edited 03-09-2001).]