What's up? First time posting here and I need some advice. Tomorrow I am picking up a 1994 Alfa Romeo 164LS 3.0L V-6 automatic. It has over 206,000 miles on it but it was a North Carolina car most of its life and very well maintained. The previous owner used only OEM parts and kept up with the 30k mile timing belt changes that are critical for these cars to keep running. He used M1 15W-50 and OEM oil filters every 5000 miles. The Alfa was never driven in winter but I will need to drive it during the winter. The factory recommends 10W-40 oil. Would it be a good idea to switch to 10W-40 for the winter and back to a 50 weight in spring? Also, would the Castrol Edge 5W-50 for classic cars be a good switch from M1 for the summer? IIRC the V-6 has flat tappets and might benefit from the extra ZDDP found in the Castrol.