I am now using Mobil 1, 10-30 grade based on several recommendations that came from here. I would like to add that I was leaking oil, a little more than a third of a quart in my first seven hundred miles, on my 91 turbo 940 wagon. The oil leak was not new, a careful inspection showed I (and the previous owner) had been leaking for some time. I checked all the breather hoses, flame trap, and the breather box. The hoses were shot, the flame trap plugged. I cleaned everything out, replacing hoses and flame trap. My leak has now disappeared. You might want to consider that the only type of oil used in jet engines is synthetic. Your turbo does get hot.