A process for preparing an oligomeric phenolic detergent composition comprising contacting an oil soluble alkylphenol with an alkaline earth metal base, an alpha amino acid, and a C 1 to C 6 aldehyde, in the in the presence of a C 2 to C 6 alkylene glycol and a C 2 to C 4 carboxylic acid; and reacting under reactive conditions at a temperature of from 150°C to 225°C. The oligomeric phenolic detergent product can be employed in a lubricating oil.