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I am buying a 1972 31 Bertram with 1999 Cummins 330 6btas (750 hours). I had the boat survey done and everything came back good. I had the engines surveyed by Cummins and they did a "blow by test", at every rpm (every 200 rpm) increment had the reading at 2 or lower which is very good according to the Cummin mechanic. I figured that while he was there I would have an oil sample taken. Anything I should look for?

The Cummins people should tell you what the oil analysis means.. ie: high iron and copper usually indicates that the engine had not been run for a while, and when later started some rust from the wear surfaces found it's way into the oil, and high silicon might be from the engine ingesting dirty air, or possibly the presence of a sealant dissolving into the oil or an antifoam additive breakdown in the oil itself, etc.

When my report came back the analysis company had made their own comments about what each "out of normal range" item usually meant. But, if you read Tony Athen's comments in the Boatdiesel forum he does not put much emphasis on a single oil sample, because 1 - many savvy sellers will have the oil changed just before the sample was taken so there are few impurities, and 2 - the real value of oil sampling is to get a history over time of what is happening to your engine, and one point in time can not show any trends in anything.