I run 5w40 all year long. It does great. I also run 2 stroke all year long. I usually put in like 20 oz per tank. Some prefer to run it at 1oz per gallon, but I haven't noticed a difference running a bit less. I don't run any additives in the winter either. The 2 stroke seems to take care of that. Now, it doesn't get -20 cold, but it still gets cold here.