Calcium is typically related to the detergent additive packages commonly used in engine oils. Detergents are used in lubricants to aid in control of deposits and help keep contaminants suspended in the oil so they can be carried to the filter and removed. In addition, some detergent chemistries also neutralize the acidic by-products of combustion. In doing so, they function as corrosion inhibitors.

The amount of calcium typically seen in an API SM engine is close to 2ooo parts per million. This comparatively high number is typically driven by the detergent additive. To contrast this level of calcium with others engine oil specifications, consider an API SA engine oil would have no calcium (therefore no detergent additive.)

It is also important to consider that whereas a high level of calcium may be desirable due to the lubricant's detergency, too much detergent can result in an oil with a high ash content. And when it does, in addition to acting as a detergent, the detergent itself can also contribute to lubricant contamination.

a-Click here for brands types and grades included.

For details on ASTM D-2896 test method click here.