Oil analysis includes testing to monitor the rates of wear, contaminants and additives in used engine oils.

Examples of contaminants include:

  • Dirt and Dust
  • Water
  • Glycol
  • Metals
  • Fuel

Not only does oil analysis provide insight into the mechanical condition of the component, it also determines the condition of the oil itself. This type of analysis can be used to determine maintenance strategies such as optimizing oil change frequencies, filter quality and efficiency.

Some industries using oil testing include:

  • Oil and gas processing facilities
  • Marine and Shipping industries
  • Agriculture
  • Mining and Milling
  • National Defence
  • Pulp, Paper, Sawmills
  • Transportation, Fleet and Rail
  • Automotive Manufacturers
  • Construction Industries
  • Equipment Suppliers
  • Aerospace
  • Manufacturing

Engine Oil Contamination

The most common engine oil contaminants are silicon (dirt), fuel dilution and antifreeze coolant. Silicon (dirt) contamination is the most common form of contamination and causes serious engine wear due to its abrasive actions against all moving parts within the engine. If the silicon levels surpass 25 ppm, the air intake system should be inspected to locate the source of entry for the dirt and other airborne debris.

Coolant is another very common oil contaminant and probably the most serious. Water from the coolant reduces the lubricant properties causing severe bearing problems, while the glycol degrades at high temperatures and forms into sludge. Monitoring water contamination levels is unreliable, as normal engine temperatures are high enough to evaporate water over time. Keeping detectable levels as low as 0.05 per cent, coolant levels can be detected by chemical analysis and through monitoring the levels of boron, sodium and potassium in the oil.

Spectrochemical Analysis on Wear Metals and Additives

This type of analysis determines the level of wear metals, additives and contaminants in new and used oil. Done on all types of samples, levels of wear metals, additives and contaminants are trended to identify problems.

Wear metal analysis can indicate which engine components are wearing and if the wear is becoming significant. This information can make the difference between minor component inspections and minor repairs or major overhauls.

Wear metal analysis requires more than simply plotting data on a graph. Wear metals can be generated from as many as a dozen different engine parts and locations making it difficult to identify the specific part that is wearing excessively. Our AGAT Laboratories' representatives can help in suggesting additional testing to pin-point the location of the wear as well as suggest common wear areas on other similar components.

AGAT Laboratories Equipment Reliability specialists can provide at no charge to clients, technical and troubleshooting papers to assist with the resolution of equipment problems.


Viscosity is one of the most important properties of lubricating oil. It is a measurement of the resistance-to-flow of a specific temperature in relation to time and can indicate component and/or lubricant degradation. Normally, a viscosity increase or decrease from one grade to the next is a warning that the oil has reached the end of its useful life.

The two most common temperatures for lubrication oil viscosity are 40 °C and 100 °C. Viscosity is normally evaluated with a kinematic method and reported in centistokes (cSt.). In used oil analysis, the used oil’s viscosity is compared to that of the new oil specification to determine whether excessive thinning or thickening has occurred.

Acid Number/Base Number

Acid Number (AN) is a measurement of the quantity of acidic derivatives that have accumulated during an industrial oils life, such as that of a compressor, gear drive or natural gas engine and is indicative of the remaining useful life of that oil.

Base Number (BN) is a measurement of the reserve alkalinity in diesel or gasoline engine lubricants and is directly related to the detergent/dispersant additive package and its ability to counteract acids, sludge and varnish.

Acid and Base number respectively are excellent indicators of oil serviceability and should be included for all oil analyses when oil quality and service life is critically important, such as when oil drain intervals are being considered or necessary.

Monitoring the increase of AN or the decrease of BN respectively are the standards to apply.

ALWAYS FOLLOW THIS RULE: When the AN doubles or the BN is reduced by half, it is time to drain the oil immediately.


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