10w40 vs 15w50

[S4_Andy]

Hello folks,

Im a speed four owner in the uk and i am hoping that you can shed some light on the oil choice for this bike. Triumph recomend mobil 1 4t oil. The recomended oil is 15w50 however it does say that 10w40 is also acceptable in both semi and fully synthetic.

Could people tell me why they have specified the 15w50 oil as a preference over the 10w40 as the latter is more easily available. Also what are the benefits of running one over the other?

 

[Quattro Pete]

Welcome to BITOG!

You may find this recent thread somewhat useful:

https://bobistheoilguy.com/forums/posts/2302725/

 

[S4_Andy]

cheers pete but it does not seem to actually answer the question.

 

[Quattro Pete]

Well, technically an Xw-50 grade should have a higher flash point and handle extremely high temps better. However, since your bike is liquid cooled, I'm not sure it matters much as the cooling system should prevent any super high oil temps from occurring.

I'd say try both grades and see if you notice any difference in engine/clutch performance over the course of a typical oil change interval. If you can't tell the difference, then use whichever one is cheaper.