Please chime in.. I'm trying to narrow my search prior to my next oil change. Vehicle information: 1987 3.3 liter, K26 turbo, air cooled. Billet cams. 85k on the bottom end of the motor. 15k on freshened heads and turbo. Currently running old stock 15-50 Mobil 1 synthetic Oil filter: OEM or Mahle Oils that I am considering.. Various brands of V-twin oil. New stock mobil 1, 15W-50 Castrol Edge, 10W-30 Other suggestions and reasons why are very much appreciated.