Synthetic Oil

[Katlin]

Anyone had any experience with using synthetic oil (Mobil One or equivalent) in their engines? I have the 75HP 4JH3-TEs but I suspect the question is relevant to any of the Yanmars. Thanks

John Sawyer
Katlin MV34/76

[SecondWind]

As a former chemist who helped develop synthetic lubricants, I will not use anything else. It goes in all of my engines, including weed whackers. Make sure to change oil filters at recommended intervals and enjoy the long engine life (internal parts only, unfortunately). Any brand will do, as long as it is not a synthetic blend. I use Mobil1, but the mfgs. all use the same base fluid to formulate.

[duetto]

hi terry,

how about for higher mileage engines? i remember years ago, legend would have it, if you switched to synthetic oil consumption went thru the roof. fact or fiction?

[SecondWind]

FICTION. I put it in my 1986 Mercedes Benz Turbo-Diesel, which I bought used in '93 with 82K Miles on it. It now has 209K. Don't believe the "bunk" about seals either. It will however clean out all of the sludge and varnish in an engine. The major advantages are extreme lubricity at high Hertzian loading (bearing pressure) and the ability to maintain lubricity to temperatures as high as 450F (although I wouldn't push it, since thermal expansion of engine parts would cause catastrophic damage). Many new cars come standard with synthetics (Corvette, Volvo), but I don't know if any boat mfg's.supply it. You can use the same grade as any standard motor oil, anywhere (transmissions) where standard motor oil is called for. It is completely miscible with regular motor oil (i.e. you DO NOT need to flush your engine), and you can add regular oil to it in an emergency.

[Page 83]

Practical Sailor Magazine agrees: stick to regular oil filter changes (to catch any crud synthetics loosen up) follow the engine manufacturer's recommended oil change cycle (they didn't want to have any liability for saying otherwise) and use to your heart's content and pocket book's capacity. But they also say there's not much to be gained for the additional expense except possibly for long distance cruisers who don't want to be doing oil changes in the middle of a translant. I think Terry's opinion is more reliable than your average boaty-writer.