The STS is great for winter driving!

[Scotty]

Scotty- I am quite confident that the 5W-30 is perfectly fine, especially if temps are below 60'F. In fact, I believe it is encouraged for winter starting, even on the 4.9L. With the current quality of 5W-30 (API-SM, ILSAC GF4), I use the 5W-30 all the time without any trouble and exceptional used oil analysis results! What brand of oil do you use? The Northstar and 4.9 seem to be very easy on oil. One funny thing...because the NS consumes oil, the fresh quart every 1000-3000 seems to 'freshen' the crankcase. Annoying for some, but a benefit to the engine to have fresh oil introduced throughout the oil change interval. At any rate, 5W-30 should be great! If you struggle with extreme cold starting/low temps, the manual recommends even 0W-30 synthetic.

Dasher- When your 93STS became stuck, was one tire spinning, or two?

Thanks Dasher, that makes me feel better about the 5W30... And yes I feel the same way about adding the quart or two during my oil change cycle, it refreshes the oil....giving about 33% new oil..

As far as brands of oil, I try to stay away from cheap oils like CAM2 and the such.. I like Pennzoil, Mobil, Texaco, Quaker State but as long is they are good quality oils I dont think brand names matter too much.