Thursday, April 14, 2016

Oil Base Numbers

The base number describes the alkalinity of the engine oil. This number is associated with the reserve alkalinity of the oil and the detergent additives that counteract the acids produced by spent fuel and acids formed when the hydrocarbon structure of the lubricant breaks down. The detergent additives also clears up deposits that have built up inside the engine.

A common detergent additive present in many engine oils is calcium sulfonate which leaves a residue when burned. The residue is largely not problematic as it can be removed in the next oil change. It can become a problem when oil changes are frequently ignored or the period between oil drains are overextended.

Every engine oil starts with an initial base number. This base number is proportional to the amount of detergent additives contained in the oil. The higher the initial base number, the more detergent additives are present in the oil.

Just like any lubricating oil, engine oil deteriorates with time. The deterioration results in the production of acids which causes the base number to drop. The drop in base number becomes a threat when it drops to around fifty percent of the initial value. It is at this point that an oil change must be performed. If the oil change is delayed, the oil can start to become more acidic and can cause corrosion of engine components.

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