Sure but if it's motul it will be expensive... I could switch to a semi synthetic but the yamalube is not a bad price, and as it's the recommended lube for likes of yammy dirt 4strokers like WR's it should be fine in the ole XR. Both the motul and yamalube I mention above are 10w40, I'm just...
I have been using motul 300V in an older xr250r the reason being to keep oil temps down (this model cracks heads when thrashed) 300V is very expensive out here (New Zealand). I was going to switch to yamalube fully synthetic 10W40 which is cheaper but I have a little motul left I'd be mixing 1L...