>As many of you know, American Diesel strongly recommends the use of Marvel Mystery Oil to accomplish the same thing in those Lehmans. This will probably generate a bunch of "not true" posts but in fairly recent industry comparison tests-- some of which I believe have been posted to T&T in the past as well as other forums--- Marvel Mystery Oil has been shown to actually reduce lubricity in some situations. It certainly doesn't help it according to the test results. If increased lubricity is what is needed--- and as many fuel "experts" say lubricity is not an issue in today's diesel fuel as say it is--- Marvel Mystery Oil does not seem to be what you'd want to use. We use a mil-spec lubricity additive that was recommended when we bought the boat by both the diesel shop we use as well as a good friend who was a design engineer for one of the major marine engine and generator manufacturers for 30+ years. I have no idea if this additive is helping or not doing anything but it's certainly not hurting--- our engines run the same with no increase in oil consumption (a quart or less every 100-150 hours) or fuel dilution in the injection pump lube oil. They start immediately and run smoothly from idle through cruise rpm with no smoke (except at startup-- it IS a Ford Lehman, after all :-) So I'd recommend learning as much as you can about MMO before using it. I would never use it in any engine I owned. ______________________________ C. Marin Faure GB36-403 (grp) "La Perouse" Bellingham, Washington