I think Lee meant 0w30 and not 5w30, and btw m1 0 weights are some of the best 0 weights you can get, especially in 30 weight and twenty weight as well. I find it very funny the dealer is using m1, that is a nono, if they can use something against the owners manual so can you. Keep that reciept. But, if you want the cold protection I say run 0 weight, but yeah 0w30 m1 is one of the best oils out there and really safe to run all year. Yes, likely 0w20 will be ok too, but I don't subscribe to running twenty weight because of what we have seen in the Cams. Especiilay if you whale on throttle once in a while or tow at all, then no 0w20 would be no good, but if you are just commuting with the truck, it wouldn't be that much different then 5w20, do a uoa as suggested, look for how much the oil sheared away from the 9 cSt. If it ends up 7 or below, I'd say I wouldn't do that again. One reason why ram has people on 5w20 is because of how stable that oil is, 99% of the time it wont shear down a full point. With 0w20 you have a little more risk of shear, I'm not sure either way, it would depend on the engine. If you are just doing it one time, don't worry, but if you are considering this as a strategy, do a uoa, or better yet, run 0w30 m1.