ira's 2000 Mystique ATX w/Religious 3K oil changes
I use the Mobile 1 filter and rotate the following oils
FULL SYNTHETICS ONLY:
Pensoil/Mobil 1/Havoline/Castrol/Valvoline
5W/30 in Summer 0W/30 in winter
For some twisted reason I have this thought that different brands have different additive packages that could clean up deposites & contaminants left by the previous. I don't run my car hard so I think thermal protection in my case is even across the board.