Used Oil Analysis
What is "Used Oil Analysis"?
A representative sample of the lubricant is taken from an engine, transmission, pump or other equipment and sent to a laboratory for analysis. The lubricant sample undergoes testing of its physical properties as well as identification of the wear metals it contains. A report is returned to the user that documents the results and suggests a course of action.
Why is used oil practice considered a "best practice"? Used oil analysis offers the following benefits:
1. Establishes safe and proper drain intervals.
2. Provides a reduction in unforeseen breakdowns.
3. Reduces profit-robbing down time.
4. Reduces unnecessary oil changes and labor costs.
5. Provides overall maintenance savings.
6. Helps increase equipment life.
7. Eliminates unnecessary overhauls.
8. May improve fuel efficiency.
9. It documents maintenance activities to support equipment warranty claims.
How can I take a good used oil sample from my engine?
Many find it most convenient to use the "drain plug method". Be certain to take the sample after the engine has been operated at normal operating temperature for several hours. Drain the oil while the engine is warm. Loosen the drain plug and let a small amount of oil drain into the drain pan before catching the sample to be sent to the laboratory. This ensures that any contamination surrounding the drain plug will not be present in the sample and influence the test results. Never take samples from the drain pan.
Wear metal tests are used to interpret the condition of equipment components. The presence of certain elements or combinations of elements indicates specific problems:
1. Tin, lead, and copper may indicate bearing wear.
2. Iron combined with chromium will usually indicate liner and ring wear.
3. The presence of aluminum may indicate piston wear.
4. Silicon can usually be traced to a faulty air intake system which allows raw air containing dirt or sand into the combustion chamber.
5. Boron and sodium are components of ethylene glycol and usually indicate the presence of antifreeze in the oil resulting from a blown head gasket, leaky oil cooler, or a cracked block.
What do the tests of the lubricant's physical properties indicate in an engine oil?
1. Levels of soot indicate combustion efficiency.
2. Oxidation effectively measures the service life of the oil.
3. Nitration measures nitrogen compounds in the oil resulting from blow-by past the compression rings.
4. High levels of ZDDP depletion indicate that the additive is being used up.
5. Changes in viscosity (a fluid's resistance to flow) from new, unused oil can indicate improper servicing, dilution, contamination or lubricant breakdown while in service.
6. Water and fuel dilution in the lubricant sample are also measured and can point to other engine problems.
Routine maintenance programs that include used oil analysis allow operators to know what is going on inside their engines, transmissions, pumps, etc.
