The S.O.S.^SM Oil Analysis tests have been developed by Caterpillar® engineers and chemists to evaluate the condition of your engines and machines, rather than the condition of the oil alone. Following is a brief description of the standard tests offered in the S.O.S.^SM program. Additional tests, such as viscosity, TBN or TAN, may be performed, if needed.

Wear Rate Analysis monitors wear by detecting, identifying and assessing the amount and type of wear metal elements in the oil. The rate at which wear metal particles increase from sample to sample is as important as the quantity of particles in the oil. For this reason, regular sampling at specified intervals is necessary to establish wear rate trends for each oil-lubricated compartment. The presence of silicon and other elements which indicate dirt entry are also monitored with Wear Rate Analysis.

Oil Cleanliness Analysis uses a Particle Count test for non-engine oil. It detects both metallic and non-metallic debris (such as friction disc material) generated by wear, as well as dirt from outside sources. This information, along with Wear Rate Analysis, permits a comprehensive evaluation of your hydraulic and power train systems. This combination can detect potential failures not identified by Wear Rate Analysis alone.

Oil Condition Analysis determines loss of the oil's lubricating properties. An infrared analysis instrument is used to compare the properties of new oil to the properties of your used oil sample. This test allows our technicians to determine the extent to which the oil has deteriorated during use and to verify that the oil is performing up to specification during the entire oil change period.

Oil Contamination Analysis determines the presence of external contaminants. Fuel, water or glycol contamination indicates problems exist that require immediate correction.

• Fuel dilution reduces the oil's viscosity and destroys its lubricating properties. Some unburned fuel may enter the crankcase past the piston rings, particularly if the engine is run at low idle for extended periods during cold weather. Fuel dilution beyond 4% by volume, however, can lead to piston ring sticking and failure of the engine bearings.
• Glycol (coolant) contamination causes rapid oxidation of the oil and will lead to a major engine failure if not promptly resolved. Water can contaminate an oil system by leaking in from the outside or condensing within a hot oil compartment or engine crankcase. Water will cause the oil to form a sludge which can plug filters.
• Oil contaminated with water passing between close fitting moving parts will cause "hot spots" leading to reduced component life or rapid failure.

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