It's hard to beat Shell Rotella, or one of the other oils intended for farm tractors or over-the road Diesels. Lately, I've been running "Traveler" brand oil in 5-gallon pails from Tractor Supply in everything we own, from cars, to trucks, to lawn mowers and motorcycles. I'm using 15W-40, but they've also got it in heavy duty 30 weight.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!