[newoldguy]

Adrial - I'd definitely drop down to 10-40 or 10-30 in the winter. You want to have the best opportunity for "flow" at start up as you can get.

Personally, for my regular cars (I don't drive the 944 in winter here) I put in 5W-30 in the winters, 10W-30 in spring and fall, and 20W50 in summer. Yes, I do change every 3 months regardless of mileage. Like the ad says, "pay me now or pay me later". For what its worth, there is an '86 Mazda B2000 over in Portland Oregon that had this treatment with 220,000+ miles on it and never had the valve cover off.

And, yes, get a good oil filter. There is a difference in quality and construction. The price difference is minimal if you consider the long run. In the future, watch the magazine or internet ads and buy half a dozen or so. Sometimes you can get a discount on 10 or 12. What the heck, if you keep the car you'll be needing them!

One final note - oil changes are definitely not the glamorous part of car ownership. It would be a LOT more fun to be installing something that would give you more horsepower. However, there is really nothing more important to insure long engine life than oil changes.
Curtis