Fascinating discussion, and one I'm very interested in right now. Especially MikeyMo's thoughts, since we own similar boats, but maybe not the same engines. I have just bought a Sabre 34-I (1979) with a Volvo MD11C, and the manual recommends 20W30. Can't find it anywhere (Pep Boys, Advance, WalMart, Sams, West). What do other users of Volvo's use?
1979 Sabre 34-I #063