AMSOIL Marine Diesel 15-40 Synthetic Oil is now approved for Volvo Penta D1-30 Engines. There are a dozen excellent synthetic oils on the approval list, and AMSOIL looks like the BEST oil in basic graphs & stats. They invented the stuff and have been around the longest, dealing with synthetic oil. AMSOIL is strictly special order, so stores can't carry it. I've never used it before. But since it's highly approved, it's on the top of my next service check list of items to get! Non-Synthetic Diesel Engine Oil cooks. It never could handle the heat, but that's all we ever had. Synthetic Oil may cost more, but it actually keeps your little diesel young!
Bill