How often should I take an oil sample on my propulsion engine or generator? We get this question quite often. The simple answer is “at each oil drain.” The power of oil analysis isn’t in a single sample-it is in observing the trend over time.
For example, if you were to sample an engine’s oil on three successive oil drains you might note that iron and chromium (wear products) and silicon (a contaminant) are in-spec and conclude that your engine is fine. However, if you were to compare these same results side by side and see that all three are trending upward (though still in spec), you could have a serious problem.
On a single sample the analyst wouldn’t flag the iron, chromium, and silicon levels because they were in spec. But if the analyst saw a trend over a couple samples taken at comparable intervals, they would immediately flag the trend and provide advice on remedial action. In this case, the analyst might suspect an air leak caused by a loose air intake fitting or a damaged air filter element that is allowing un-filtered air to enter the turbocharger and combustion chambers. The result is accelerated wear to valves, cylinder liners, piston rings, bearings, and other engine components that reveals itself in upward trending wear metal concentrations.
Unchecked wear reduces the life of your engine and its reliability. Routine oil analysis provides peace of mind and allows you to cruise with confidence!