i was talking to a vw machinist the other day while ordering up a new transmission and the subject of oil and oil pressure came up first off his rule of thumb is 10 psi for every 1000 rpm and he did not recomend synthetic oil in air cooled motors as he had seen tests showing synthetic oil moving away from heat wich is a bad thing for air cooled motors which use oil to help cool the engine my recomendations is to use aero shell aircraft oil in aircooled motors and fit te engine with engine oil prheaters like tannus heaters to give you guick lubracation on start up aero shell is specificaly made for aircooled motors wich are put tocether looser and are subjected to a lot more heat extreems.