So is there a difference between a 10w40 bike oil and a 10w40 car oil? I seen another thread about synthetic oils, but is oil for dirt different?
I have an 03 Yami YZ250F and since theres relatively no difference between brand X and brand Y car oils (assuming both are synthetic or of equal make) is the same true for bikes?
Judging by the graphs in that other topic, Ill just pick up some castrol or some Mobile 1.
Also what is 4R oil? What does that mean?