I was running a mix of Mobil One T4 10w-40 and 15-50 in my Triumph R3 this last winter and spring. This bike is also liquid cooled.
We are supposed to put Triumph T4 Racing oil in it. That oil is hard to find, usually only available at the stealer for a ridiculous price.
So I changed out the mix and put in Mobil V Twin 20-50. My previous experience with the Mobil V Twin was with a Victory Hammer V Twin and it was good.
The Hammer was air/oil cooled with a factory cooler installed. It ran great with the Mobil V Twin 20w-50.
My Triumph R3 really likes the V-Twin. I run her hard for about 200 miles this last Sunday in 90 degree heat, mostly high speed. The R3 ran great.
I have no scientific proof, but I think I am going to stick with the V-Twin, instead of the T4 15-50 for hot weather riding.
Engine seems to run a little cooler and the shifting is spot on.
Yeah, give the V Twin a shot. What could it hurt? You can always change it out, if you are not happy with it.
The 10w-40 and 20w-50 are both easier to find. I buy mine at autozone.