Basic question
- Thread starter thiggy
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Total Base Number (TBN) is the measurement of a lubricant’s reserve alkalinity, which aids in the control of acids formed during the combustion process. The higher a motor oil’s TBN, the more effective it is in suspending wear-causing contaminants and reducing the corrosive effects of acids over an extended period of time.
Oils within an engine tend to deteriorate due to reasons of temperature, fuel ingress or other sources of contaminants forming harmful deposits. These deposits can build up behind piston rings, on ring lands, under the piston crown or on sliding surfaces. The net result is sticking and increased wear. Lubricating oils contain detergents and dispersants to delay the formation of these deposits and reduce the rate at which they form. Detergents are generally considered as those compounds that neutralise the deposit precursors that form under high temperature and pressure conditions or as the results of using high sulphur fuel. Dispersants on the other hand are those compounds that disperse or suspend the deposit forming contaminants. However in reality there is no sharp line of demarcation between the two.
The principal detergents are soaps and salts of alkaline metals, usually calcium in the case of marine oils; they are often referred to as matallo-organic compounds such as sulphates, phenates and salicylates. These compounds are usually "over based". They contain more alkaline metal than is required to neutralise the acidic components used in manufacture of the additive. These are usually ash forming and spent additive will contribute to the insolubles loading in a used oil.
Typical dispersants are usually "ashless". They do not form ash on combustion. They have fairly unpronounceable names such as polymeric succinimides, polyesters and benzylamides. The molecules have a polar or charged end that will attract and hold on to potential deposit forming compounds keeping them in suspension in the oil.
The TBN additive will neutralise acidic combustion products, they will also neutralise deposit forming compounds within the oil, hold them in suspension preventing deposition and with luck also remove any deposits that are formed. Have you ever seen the results of a lubricant trial described in the technical press where you have a before and after picture of a nice clean piston? That is a direct benefit of these TBN additives.
Oils within an engine tend to deteriorate due to reasons of temperature, fuel ingress or other sources of contaminants forming harmful deposits. These deposits can build up behind piston rings, on ring lands, under the piston crown or on sliding surfaces. The net result is sticking and increased wear. Lubricating oils contain detergents and dispersants to delay the formation of these deposits and reduce the rate at which they form. Detergents are generally considered as those compounds that neutralise the deposit precursors that form under high temperature and pressure conditions or as the results of using high sulphur fuel. Dispersants on the other hand are those compounds that disperse or suspend the deposit forming contaminants. However in reality there is no sharp line of demarcation between the two.
The principal detergents are soaps and salts of alkaline metals, usually calcium in the case of marine oils; they are often referred to as matallo-organic compounds such as sulphates, phenates and salicylates. These compounds are usually "over based". They contain more alkaline metal than is required to neutralise the acidic components used in manufacture of the additive. These are usually ash forming and spent additive will contribute to the insolubles loading in a used oil.
Typical dispersants are usually "ashless". They do not form ash on combustion. They have fairly unpronounceable names such as polymeric succinimides, polyesters and benzylamides. The molecules have a polar or charged end that will attract and hold on to potential deposit forming compounds keeping them in suspension in the oil.
The TBN additive will neutralise acidic combustion products, they will also neutralise deposit forming compounds within the oil, hold them in suspension preventing deposition and with luck also remove any deposits that are formed. Have you ever seen the results of a lubricant trial described in the technical press where you have a before and after picture of a nice clean piston? That is a direct benefit of these TBN additives.
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