Oil analysis is an invaluable tool, but often misinterpreted

I once read an article in a major boating magazine entitled “Oil Analysis Made Simple.”

- STEVE D’ANTONIO

It caught my attention because, as a trained oil analyst, I know from experience as well as formal training that oil or fluid analysis is complex and fraught with both opportunity for sampling errors and misinterpretation of reports. It’s little wonder the science of oil analysis is frequently dismissed by industry professionals, especially brokers, as unreliable and a black art; in many cases, they have good reason to question the results.

In practice Lubricating oil is the very lifeblood of an engine: Without it, gears and bearings would quickly overheat, seize and grind themselves to a halt. In addition to lubrication and heat removal, as oil courses through an engine it picks up and carries with it contaminants, from moisture and carbon to metal, coolant and fuel — all of which can be identified and analyzed. In doing so, and when carried out properly and accurately, this analysis can reveal a great deal about engines and other equipment. I frequently refer to this analysis as the mechanic’s (and boat owners’/buyers’) crystal ball.

The return on investment where fluid analysis is concerned can be substantial. Analyzing a few ounces of crankcase oil, for instance, can yield reams of information about the current health of an engine, and how it has been maintained throughout its life. For instance, sodium (typically but not always considered an external contaminant, as it is contained in some coolant mixtures), when found in an engine’s lubricating oil, may be indicative of ingestion of salt-laden mist. This can happen if spray is ingested into an engine room air intake. By contrast, wear metals such as iron, chrome, nickel, copper, lead, tin and aluminum each tell a different story about a component within the engine, from pistons and rings to bearings and valves.