Lube Condition Indicators
"Oxidation" is a general term used to describe the degradation of the basic lube product as a result of operating temperatures and/or churning with the air. Generally, oil thickening is associated with oxidation. Organic acids are prior to and during thickening, which can be detected by TAN increase. Oxidation of lube is not only significant from the standpoint of thickening, but the lubricating quality (lubricity) of the lube itself can also be reduced.
"Corrosive Acid" is formed primarily from sulfur blow-by products in the combustion process. Any amount of water contributes toward activating this acid to the point of parts corrosion. The formation of corrosive acids in engines is unavoidable, but alkaline (basic) materials are added to motor lubes to counteract the acid upon entry into the crankcase. corrosive acid in non-engine systems is usually an environmental problem. One exception is the formation of corrosive hydrochloric acid in refrigeration systems, where freon deterioration may occur in the presence of moisture.
Total Base Number (TBN): TBN is the amount of alkaline material (generally as corrosive acid neutralizer) in the lube, commonly referred to as "Alkaline Reserve".
Significance: TBN is of primary concern in motor lubes, .as additives are placed in the lube when it is blended to neutralize corrosive sulfur acids formed in the crankcase in the normal process of combustion. Measurement of TBN allows one to know if the starting additive package is still capable of counteracting combustion acids; therefore, TBN is an essential element to the safe extension of lube drains.
