I bought a twin engine turbocharged diesel about two years ago, and always had vibration in the starboard engine. The mechanics blamed the harmonic balancer and a variety of other issues. I could not sync the engines until I put in electronic tachs!

This weekend, the vibration increased, and a knock became very noticeable. I had visions of pulled injectors, and maybe, pulled a head. A friend recommended Redline (sp?). I could not find it, but found Marvel Mystery Oil. It said it did the same thing as I was told Redline did. Another friend, a longtime diesel mechanic, told me he used it for years while running a gas station to fix my very problem. I was skeptical. I have not believed in magic additives.

We added eight ounces to each engine main fuel filter (Racor 500s), and started the engines. We idled to the main channel and ran for five minutes at 1200 RPM.

No vibration.

We then ran for a time at 2000 RPM. No knock. No vibration. I could sync by ear on the flybridge. Both engines ran smoother than ever before. I looked over the stern and found no exhaust smoke! At that point, I poured the recommended mixture into the diesel fuel. We ran at many other RPMs for about another hour. Still smooth. When I returned to the dock, I checked the exhaust at idle. NO SMOKE!

I had been anticipating having to have the injector pumps adjusted.

I am now a beliver. MMO will go in with every fillup.

It's also going into my 1986 pickup.