In article xGEic.24898$IW1.1210282@attbi_s52,
Scott Lowrey wrote:

The DE asked, "What kind of oil do you put in the airplane we're going
to fly?" I told him the plane used 50 weight ashless dispersant oil.
He replied that the plane actually used 100 weight oil. I was pretty
sure he was wrong but I let it go.

Shell has a lot of publications about aviation oil on their website.
Among other things their FAQ mentions that you can mix any of their
oils, so you don't have to know what's in the plane, you can put in
anything suitable.

--
Ben Jackson

http://www.ben.com/