we've had pretty much the same weather in StL and i have had no problems. it takes a little bit to crank over, but that's it. i'm running mobil 1 10w30 without problems. sometimes i let it warm up and other times i warm it up with gratuitous use of the throttle. i havn't really noticed a diff b/w the 2. my mileage sux though that's to be expected.