Engine life has been a discussion point numerous times here on T&T. I don't recall the following being discussed. At http://www.yachtsurvey.com/GasNdiesel.htm David Pascoe says: "...There is a very simple formula you can apply to estimate service life: simply multiply the cubic inch displacement of the engine times one. The result is the maximum amount of horse power you can have and still expect a reasonable service life. A 6V92 engine is 552 CID; at powers greater than 550, these engines don't last. At 450, they'll go 10 - 15 years easily..." We recently surveyed a yacht with a pair of 8V71N (naturally aspirated) Detroit Diesels rated at 325 hp that hadn't been overhauled since new 1981. Now, an 8V71 has a 568 cubic inch displacement; the fact that these engines have a 0.56:1 power/displacement ratio explains why they could run so long. "...divide the CID by the horse power, and the greater the result UNDER the factor of one (1), the longer engine life you can expect. If you have an engine with an 0.70 CID/HP ratio, then you can expect 3000 hours engine life. Otherwise, you are a victim of the myth....(of eternal diesel hours)..." He was discussing recreational engines above, NOT commercial, and he claims recreational engines suffer corrosion from long periods of non use which shortens engine life. Rob Brueckner Hatteras Yachtfisherman