Well,..
If you dont wanna use syns or read the links that explain things in detail:
Use Valvoline Durablend 10w-40.The durablend is good solvency, good anti- wear properties, it a bit moe expensive than the all mineral oils, but not as as much as a syn.Also its easily avalable everywhere and a good stable 40 weight which you are likely to need with your VG (maybe even thicker as its an older VG series engine)
Also read the links, there are some lenghty viscosity discussions in there on why not to bother w/ 30 weights in most applications.
Fred..
