Oil and Lubrication
I picked up 250 dirt bike to play with. It's a 4 stroke & air cooled.
Lots of guys on the dirt bike forums suggest Rotella T6, 5w40.
Book calls for 10w40
Being in the South, 5w40 seems thin. Also, the T6 is listed as a diesel oil and has "some" friction modifiers, bad for wet clutch.
So why do...