Contaminants will corrupt any lubricating system, but quality lubricants can reduce contamination and extend oil service.

There are four ways contamination occurs in lubrication systems:

  • First, the system itself can generate contamination through poor system or component design, temperature related chemical reactions or just normal use.
  • Second, contamination can be caused by careless packaging or handling of components before or during installation.
  • Third, contamination can be introduced though improper or careless maintenance.
  • Fourth, contamination can be caused by another system leaking into the first system.

Base oils possess a varying degree of solvency (the ability to dissolve a solid, liquid or gas), which assists in maintaining internal cleanliness. However, commonly paired detergents and dispersant pairings maintain internal cleanliness by:

  • suspending contaminants,
  • minimizing contaminant clumping (agglomeration)
  • preventing contaminants from adhering to components.

Over time, degradation of the oil can result in a cleanliness issue, but oxidation inhibitors can reduce this effect.


Detergents added to lubricants minimize deposit formation in the high-temperature areas of an engine. The most used detergents in motor oil formulations are metallic (ash) soaps with reserve basicity to neutralize the acids formed as byproducts of combustion. Other detergents include metalorganic compounds of sodium, calcium and magnesium phenolates, phosphonates and sulfonates.

Dispersants are additives that help keep solid contaminants in suspension. By keeping contaminants suspended within the lubricant, sludge, varnish and other carbon deposits are prevented from forming on engine parts. Dispersants also prevent contaminants from agglomerating into larger and potentially dangerous particles.

Dirty components run poorly, pollute and don’t last. They cause system failures in engines, compressors and gear box systems that dramatically increase downtime, increase operating costs and reduce equipment life. Clean lubrication systems, on the other hand, require less maintenance, produce more energy, use fuel more efficiently, increase equipment service life and run cleaner.

AMSOIL lubricants use detergent and dispersant additives to significantly reduce sludge and carbon deposit formation better than conventional oils.

Total Base Number (TBN)

One way to know how well a lubricant can protect your vehicles and equipment is to look at the total base number (TBN). This number indicates its ability to neutralize contaminants such as combustion byproducts and acidic materials. It is a measure of (alkaline) additives in the oil. Higher-TBN oils can neutralize a greater amount of acidic materials, which results in improved protection against corrosive reactions.

TBN levels are targeted for the intended application. Typically, gasoline engine oils display lower TBN numbers, while oils in a diesel engine must manage the heavy contaminant loading from soot and sulfur and usually run higher.

TBN levels decrease as the oil remains in service. When the level reaches a point where it can no longer protect against corrosion, the oil must be changed.

Oils that are formulated specifically for extended drain intervals typically display elevated TBN numbers to ensure proper corrosion protection for the duration of the extended interval.

Base Number Test (ASTM D2896/ ASTM D4739)

The Base Number Test measures the detergents and dispersants in new oils. Two tests are commonly used in the industry to calculate TBN. ASTM D2896 typically results in slightly higher TBN values than ASTM D4739.

AMSOIL Advantage High TBN

AMSOIL lubricants contain high TBNs, they neutralize acidic contaminants formed during the combustion process and keep these contaminants in suspension to prevent corrosion.