Realize the full benefit that used oil analysis has to offer!

Inspect sample bottle for contamination.

Samples should be taken at or near normal operating temperature.

Take samples in the same manner from the same point each time.

Provide complete and accurate information on the sample label provided.

Be on a regular and continuous sampling program.

Cut open and inspect oil filters each time.

(Particles seen by the naked eye are too large for analysis and may indicate imminent failure.)

Wear Metals

Interpretation of used oil analysis is based upon trending; therefore to interpret the condition of a component properly, a history of tests is required. However when no history is available the general rating system listed below is useful.

Level Allowed
Lead: Overlay on bearings; in gasoline engines from fuel 40
Copper: Bearing and bearing cushion wear; Additive in some oils 40
Iron: Crankshaft; Cylinder walls; Rings; Sleeves or Valve train 100
Chromium: Chromed parts such as; Piston rings or Valve stems 20
Tin: Overlay on bearings 40
Silicon: Dirt; (Very abrasive element, high levels contribute to excessive wear and shortened component life.) Additive in some oils 20
Aluminum: Piston; and Bearings 40

Additive Metals

Lubricating oils are formulated with many different types of additive packages, fulfilling the manufacturer’s specifications for components and their applications. Changes in additive levels may indicate the use of an incorrect type of oil, or a mixture of oils in service.

Anti-Wear additive

Phosphorus: Anti-Wear additive

Barium: Detergent / Dispersant additive

Magnesium: Detergent / Dispersant additive

Calcium: Detergent / Dispersant additive

Physical Tests

The following tests are performed on a FT-IR spectrophotometer. The used oil is compared to the unused oil; therefore it is essential that the laboratory have, on file, an analysis of the fresh (unused) oil. When no such reference oil is provided, the computer uses a “best match” to determine results.

The quantity of fuel soot is an excellent indicator of combustion efficiency. Indicates injector malfunctions; air intake restrictions; over loading; or excessive idling. Most manufacturers recommend corrective action at levels above 6.0%.

The amount of oil oxidation is an excellent measure of the effective service life of the oil. Indicates internal overheating; extended drain interval (aging). Results are reported in absorbance/centimeter (abs/cm).

Nitration is a measure of the nitrogen compounds in the oil resulting from blow-by past the compression rings. Indicates improper air/fuel ratio; low operating temperature Results are reported in absorbance/centimeter (abs/cm).

ZDDP Depletion:
Zinc diothiophosphate is an additive in the oil that provides a protective film. High levels of depletion indicate that the additive is being used up. Results are reported in absorbance/centimeter (abs/cm).

Water in the oil prevents proper lubrication and causes sludge formation. Indicates coolant leaks; condensation due to low operating temperatures; inadequate crankcase ventilation. Results are reported when the level exceeds 0.3%.

Fuel dilution is the primary cause of oil thinning, and greatly reduces lubricating ability. Indicates leaking fuel pump; lines; injectors; or excessive idling. Most manufacturers recommend corrective action at levels above 4.0%.

Ethylene glycol in the oil causes serious varnish and sludge formation. Indicates loose or cracked head; block; leaking gaskets; sleeve seals; or oil cooler. Results are reported when the level exceeds 0.1%.

Measures a lubricants resistance to flow. Changes in viscosity indicate improper servicing, dilution or contamination, and lubricant breakdown in service. SAE grades are described as follows SAE (10w) < 5.6, SAE (20) 5.6-9.3, SAE (30) 9.3-12.5, SAE (40) 12.5-16.3, SAE (50) 16.3-21.9. Condemning limits are +/- 15% of the new oils value. Test results are reported in centistokes (cSt).

Total Base Number (TBN) represents the quantity of alkaline reserve which is capable of neutralizing any acidic by-product in the oil. Low results are usually related to high sulfur fuel. Results are reported in mg KOH/g.


Physical tests measured in absorbance/centimeter (abs/cm) can be described in the following manner.

Good Fair Poor
0-50 50-100 100+

The symbol (<) refers to “less than”

View Test Results

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