The following letter was reprinted from Practical Sailor

While the verdict certainly isn't in yet on synthetic oil and the controversy bubbles along in the PS Advisor column (August 15, 1993, and December, 1994), maybe the answer is a mixture of both synthetic and petroleum-based lubrication. In assembling and test running Perkins Diesels, we've determined with heat sensors and visual inspection that petroleum fortified with synthetic oil gives the best of both worlds. We gained the advantages of synthetics without the rapid drain-off from engine castings (leading to dry starts). We've used the same fortifying process for transmissions with equally good results.

Jay W. Foley
Foley Marine and Industrial Engines