The invention relates to phosphorous-containing compounds useful as antiwear additive components, lubricant additive compositions and lubricant compositions each comprising such compounds, methods for making and using the same, including methods of lubricating machines and machine parts and methods of extending the useful life of elastomeric seal components of such machines.

To provide a lubricant composition for shock absorbers, a friction adjusting additive for a lubricant for shock absorbers, and a lubricant additive, each capable of satisfying both operational stability and ride comfort and improving the ride comfort further. The lubricant composition for shock absorbers contains a base oil and a friction adjusting agent and the friction adjusting agent contains a first zinc dithiophosphate represented by the following formula 1:

##STR00001##

[in the formula 1, R.sup.11 to R.sup.14 are alkyl groups in which one or more and three or less is/are a primary alkyl group and the other(s) is/are a secondary alkyl group].

The invention relates to phosphorous-containing compounds useful as antiwear additive components, lubricant additive compositions and lubricant compositions each comprising such compounds, methods for making and using the same, including methods of lubricating machines and machine parts and methods of extending the useful life of elastomeric seal components of such machines.

The invention relates to phosphorous-containing compounds useful as antiwear additive components, lubricant additive compositions and lubricant compositions each comprising such compounds, methods for making and using the same, including methods of lubricating machines and machine parts and methods of extending the useful life of elastomeric seal components of such machines.

The invention relates to phosphorous-containing compounds useful as antiwear additive components, lubricant additive compositions and lubricant compositions each comprising such compounds, methods for making and using the same, including methods of lubricating machines and machine parts and methods of extending the useful life of elastomeric seal components of such machines.

To provide a lubricant composition for shock absorbers, a friction adjusting additive for a lubricant for shock absorbers, and a lubricant additive, each capable of satisfying both operational stability and ride comfort and improving the ride comfort further. The lubricant composition for shock absorbers contains a base oil and a friction adjusting agent and the friction adjusting agent contains a first zinc dithiophosphate represented by the following formula 1: ##STR00001##
[in the formula 1, R.sup.11 to R.sup.14 are alkyl groups in which one or more and three or less is/are a primary alkyl group and the other(s) is/are a secondary alkyl group].