I use Castrol GTX 20-50 summer and 10-40 winter. Arizona car. I agree with Matt.
tdskip, "Manuals haven't arrived yet so thanks for bearing with me on the question and you'd be surprised at how little on this topic Google comes up with..."
If you need additional information and become an expert:
http://forums.pelicanparts.com/showthread.php?t=367300&highlight=engine+oil+thread
GL
John_AZ
1988 924S + 1987 924S