An Eye into Your Engine

An Eye into Your Engine

Oil analysis is a simple, inexpensive, and invaluable tool for getting the most out of your marine engines and gears.

By Craig Anderson - January 2004

 More of this Feature

• Part 1: Oil Analysis
• Part 2: Oil Analysis

 Related Resources
• Engines Index

Crude oil—who would have thought that the byproduct of a million millennia of decomposing vegetation and dinosaurs would end up changing the world’s maps, its economy, and a slew of other pretty important stuff, including how we get from point A to point B?

Part of its success is due to the fact that crude oil can be refined into so many useful things. The subject of this article is lubricating oil, the stuff that keeps engine parts from rubbing up against each other and melting, and what it can tell you, as opposed to what it does. While there are different types of oil for different engines, all engines need lubricating oil, and all except two-stroke outboards employ that oil by circulating a supply of it through their components. Because lubricating oil is formulated not only to lubricate but also to hold contaminants in suspension until it is replaced, a sample of it can provide a picture of an engine’s condition at any particular time. The way to unlock such valuable information is through oil analysis, a process that can involve three kinds of scientific testing: spectrographic analysis, particle counting, and ferrography.

Spectrographic analysis goes by either of two names: Inductively Coupled Plasma Optical Emission Spectroscopy Analysis or Infrared Spectral Analysis. But all you need to know is that in both, oil is burned by high voltage or flame, and the wavelength of the resulting light is analyzed to give you precise measurements of whatever is in the oil that wasn’t there when it was new. Each element that appears corresponds to a different contaminant and thereby a different engine situation. Caterpillar/H.O.-Penn in Connecticut, for example, uses spectrographic analysis to determine 13 potential wear elements. High levels of iron, chrome, and aluminum, for instance, might indicate piston ring or liner wear, while high amounts of copper or aluminum may point to bearing wear. Abnormal sodium or potassium levels could mean you have a faulty gasket or possibly a cracked cylinder head, and so on. Spectrographic analysis can also determine the presence of water, fuel, and organic (nonmetallic) material that may be the result of excessive oxidation or nitration. You can use this information to determine optimum oil-change intervals. That’s important everywhere, but especially in the Northeast, where boats may not be used as much. Up there, oil can become highly acidic and therefore corrosive; analysis can show whether fogging or other recommended winterizing steps are really protecting your engine against such destruction.

Although spectrographic analysis is excellent at detecting small amounts of contamination, it’s not so good at dealing with larger particles. That’s where particle counting comes in. Here oil is simply passed in front of a strong light, and a detector determines the amount of light passing through it. This information can be converted into the amount of particulates present. High amounts of particulates may indicate the presence of unburned fuel, combustion blow-by, or faulty filtration.

Next page > Part 2: Best of all, the cost for all this is moderate. > Page 1, 2

This article originally appeared in the December 2003 issue of Power & Motoryacht magazine.

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