quote:Nope...in fact, I strongly recommend that you run a 40-weight in that engine!
Originally posted by Stewart Fan: There are very few UOAs done on the 8.1 liter gas engines from GM. All the UOAs have been on M1 10-30 IIRC. Although my truck calls for a 5-30/10-30,I'm going to try the 5-40 M1,and post a UOA in a few months. I don't see an issue with the higher viscosity. A COLD winter night around here is 25-30* Fer. The average overnight lows are around 40*. Do you see any reason not to try it?