Not so much a best oil comment but more so a whats the cheapest half decent full synthetic oil that is 10w40. I've been a rotella T6 fan for all my years of riding and never had an issue, but now the bike has a warranty and its a long one to boot.
That also with the fact that a 5w40 should by all rights break down faster than a 10w40, and the factory suggests 10w40, not sure if it could ever be an issue since it is JASO MA rated but id imagine if i busted something while trying to run 20w50 in the cold it would not be covered for what id call fairly obvious reasons. I just figure with the fact it could be perhaps be an issue and the fact a 10w should last a bit longer, i'll just pay the price difference unless I knew for sure that good old T6 would never cause a problem with warranty work.
Cheapest I have found so far is 4L Motul 7100 from GP Bikes for $60. Sure you can get it off them for cheaper than that with coupons but for sake of argument lets call it $60.
Does anyone have a full synthetic 10w40 for cheaper?