Originally Posted by ericgrau

ultrataco: pay attention to Aaron_Cake on this one. 20w50 in below freezing weather is definately a no-no. Your engine will wear a lot faster since it will hardly have any oil during startup. "Seeing how it goes" isn't a good policy, since your engine will be fine until it finally wears out early.

To anwer the original poster. No, I doubt the oil weight makes any difference at all here (nor does it do anything at all in the short term, for that matter). Thicker oil does flow slower and therefore leak slower, but even if that were the case you're only reducing the problem a little by using thicker oil. That won't fix it.

10w40 is slightly worse than other grades because it has more viscosity additives (and less of everything else). Ditto for other wide temperature range oils. Frankly, though, I wouldn't worry too much no matter what you use. Anything between 10w30 and 20w50 is good. I'm switching down to 10w30 myself because it gives slightly lower friction and it flows a little better during startup (to get your unoiled engine oiled up right away). 20w50, OTOH, seals a little better and it coats better after startup (to give a thicker layer of oil on all your parts).