Any of you running 0w30 castrol have gas mileage decrease or notice the engine more sluggish compared to 5w30? I'm running 5w30 syntec in my LS integra, and was thinking about switching to 0w30 year round. The car sees some track use, so I feel better about it being a little bit thicker for better film strength, but the 0 weight should help when it drops to -20 like it has been.

Has anyone noticed a drop in either mileage or performance with this stuff? I'm seafoaming the motor to try and boost my MPG, and dont want to undo what I've done if the oil is too thick.

Thanks