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Boating Know How Testing Engine Oil
Keep a boat engine working with an annual oil test.
Dirty oil, disgusting as it is, can tell you a lot about an engine. Contaminates trapped in the oil are similar to the growth rings of a tree or the fossil record found in the earth's sediment. The oil collects and stores the metal particles and contaminates between oil changes creating a snapshot of the engine's condition. Major trucking fleets, construction companies and fishing fleets all use oil analysis as a critical maintenance tool. At least once a season or at each oil change you should have your engine's oil analyzed to head off developing problems.
The labs that analyze oil produce slightly different reports, but they all test for suspended metals that indicate wear, and the physical properties of the oil to determine its lubricating ability. The analysis measures these contaminates in parts per million by weight so even a properly running engine will have some suspended metals in the oil.
Each engine has different wear rates and a lab has base line data for various types of engines with similar operating hours and indicates which amounts are out of line. With a record of several oil analyses you can establish a trend for your engine noting any increase in contaminate levels.
A laboratory test reports on a long list of metals that are associated with wear from specific engine parts. For example, aluminum and chromium are associated with piston and piston ring wear. Copper and tin metals deposits come from bearings, bushings and valve guide wear. Iron deposits may come from camshafts, crankshaft, cylinder liners, valve train and timing gear wear. Lead can indicate bearing wear. Silicon comes from dirt that passes through the air cleaner or crank case breather. Sodium may indicate a coolant leak.
The physical properties of the oil itself is an indication of how well it is performing. For example, viscosity shows how easily the oils flows. Oxidation and fuel effect this measurement because the oil's oxidation level measures varnishes, gums, and other contaminates created if the oil got too hot, or was left in service too long. Antifreeze or glycol in oil will contribute to oxidation and high acidity in the oil. Fuel in the oil lowers its viscosity and lubricating properties.
Boron, magnesium, calcium, barium, phosphorous and zinc are usually contained in the oil additive package, an indication of how well the oil is performing. Some analysis reports include the total base number that indicates the acid-neutralizing capacity of the oil.
Testing the oil is easy, just pick up an oil sample kit at your engine service company, parts supplier and marine store for $10-35. A typical kit includes containers for the oil samples, instructions, and a pre-addressed mailer you return to the lab for the analysis. The cost includes the report you'll receive back in the mail or by fax.
Some kits contain everything needed to draw the oil sample including a length of plastic tubing and a bellows container that draws the oil from the engine and stores the sample for shipping. Other kits supply sampling bottles and mailer; you provide the vacuum pump and plastic tubing to extract the oil from the engine. This type of kit is best for engines that provide an oil sampling port so the oil doesn't have to be extracted from the engine.
The oil analysis is only as good as the sample you send to the lab so you should follow a few key procedures. To get the most accurate sample draw the oil at normal operating temperature either while the engine is running or right after it stopped because like any solid suspended in a liquid, contaminates will settle in standing oil. If you engine has an oil sampling port, clean the exterior of the port and allow some oil to flow through it before you take the sample.
To draw oil from an engine without a sampling port, insert the collection tube through the dip stick tube into the oil pan. Don't allow the tube to go all the way to the bottom of the pan or rub against its sides where there's a higher than a normal concentration of contaminates.
After drawing the sample, cap the sample immediately. Discard the sampling tube, don't reuse it. And don't use the same vacuum pump to sample antifreeze and oil because the pump can pick up trace amounts of contaminates and pass it on.
Some labs require a sample of both old and new oil so it's important that you send the same brand and type along with the old oil. Other labs just ask for the brand and type of oil in the submission form you fill out.
A series of good oil analysis reports is reassuring for you, and should the day come when you put her on the block, be impressive to the potential buyer.
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Copyright 1999 - 2010 Perfect Partnership Inc.
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