Hello I have a 1976 anniversary edition 4108, I rebuilt the engine and installed a cast iron sleeve. And an early 80’s 6211 that I engine swapped an opposed 19.5 hp Briggs into. Both run great and use very little oil. I was just wondering what you guys use for oil. As for me I use Phillips Victory 20-50 aviation oil. It’s my reasoning that they both (piston planes and mowers) are air cooled and run near redline most of the time. Anyone have any other options?
Sounds like you are using better oil than what the OEM recommended back when new. Most all OE engines have been prescribed to use SAE 30 or 10W-30 for years.
I tend to prefer Royal Purple because I run it is all of my old Harley's. It's great oil. Other that I use Castrol GTX.
Down here in South TX, 20W 50 works perfect in any air-cooled engine.
