Many of the “big name” engine builders on RennList recommend BradPenn (PennGrade) oil so that’s what I use in my air-cooled. I love the sort of green tint to it - it’s like NyQuil. 20w-50 is standard but if you’re in a very cold climate go with a 40. If you have any weeping from your covers expect it to get worse when going to a lighter grade.
Many of the “big name” engine builders on RennList recommend BradPenn (PennGrade) oil so that’s what I use in my air-cooled. I love the sort of green tint to it - it’s like NyQuil. 20w-50 is standard but if you’re in a very cold climate go with a 40. If you have any weeping from your covers expect it to get worse when going to a lighter grade.