Penzoil Synthetic Blend is my recommendation. I have used it for some years on all my motors and have recommended it to many. Runs with less smoke and reports on it are excellent. Wally world has it in Gallon containers for $14. I have three on the shelf and will get another two this week before Wally world doesn't have it on the shelf again. I paid $16 a gallon for a 4 gallon case from Shell when Wally world didn't have it on the shelf a couple of years back. Bit of a hassle getting it through the Shell distributor.
To use the Penzoil Synthetic Blend, do I need to drain all of the old oil out? I guess you can not mix it. And once again Thank You for all your help. RV
I cannot give you anything definitive on mixing oils. I would not do it. Incidentally Wally world have just jacked up the price to $17 and change. Someone must have told them I was coming.