>>My vote would therefore be to use a synthetic, >>but at the same time also use a very excellent by-pass filter with it. That >>would be the best combination. > >Thanks - that's what I was thinking. For those interested in Mobil synthetic oil for diesel engines, it is Delvac 1, not Mobl1. The Delvac 1 has even better proerties than Mobil 1. I am strongly considering it. CaptnWil 40 Pier Pointe New Bern NC 28562 (252) 636-3601 captnwil@coastalnet.com