I know they say use 10w-30 in the winter but it seems to be giving me really bad gas mileage... does anyone use 5w-30 in the wintertime anyway for the gas mileage? i'm gettin like 16mpg

 

I'm using 5w-30 right now , I use to use 10w-30. I did not really notice a big difference.

 

there isnt much of a difference b/c at temperature both oils are 30 wt.

 

i dont think oil would effect gas mileage that much. what was it b4. are you burning oil? did you change brand?

 

You're not supposed to use 10w30 in the winter, who told you that? You need thinner oils at startup when the ambient temps are low, so the first number needs to be smaller for wintertime use, NOT larger. And everyone else is right, both oils should technically have the same viscosity at normal operating temps.