Tom - I meant 10w-30 which isn't good for up here in Anchorage and is why I think it's BS for the dealer up here to use that in the truck. It gets below Zero here, often, and that's air temp, not windchill. According to your chart I should be using at least a 0W oil. And it gets lower than your chart shows too. Granted, Anchorage itself rarely gets lower than -20F, but that doesn't mean you don't drive in colder temps. They also won't allow the 60% anti freeze to 40% distilled water, even though that's in the manual. They stick with the 50/50 mix. It's fine, I run it, the truck blowsup they'll find there stuff in it and they will pay to replace it and put me in a rental until it is.

I just put 5W-30 in the wife's car because that is the ONLY approved oil for that car I could find so I mixed the bottom number, which is even worse than a 5W oil.

 

That makes sense Dak, wasn't thinking of your climate up there to put that in perspective. I've heard more than a few folks over the years insist that 10w30 is too light for a diesel engine, but I've never seen any evidence to support that.

 

I was happy with that oil when I was in Miami. It is sorta within the chart. A 40 weight oil was "better" for the heat there... But up here, it's the opposite. The cold is the problem.

It isn't a problem when I can plug in - which I do at home. It becomes an issue when you spend the night out and can't.