Last week I purchased a 99 yz400f after taking about 14yr leave from the hobby/sport. I think I got a good deal on the bike thus I couldn't pass it up Anyways, what oil should I use? I have been told to not use synthetic oil just use 10-40 dyno oil? Any certian manufacturer? Is Castrol OK?? Change every 10 ish hrs? Is there anything else I need to know on the bike? I was going to ride my 1986 TT 225 which has sat since 91 however like I said I couldn't pass this bike up. I plan on doing more trail riding then track riding & am looking for trails in the Ohio area, Dayton is where I live.