The invention relates to specific quaternary amidoamine detergents, the process to make them, and their use. The quaternary amidoamine detergents are obtainable by reacting a multifunctional acid with an amino amine, followed by quaternization, suitably with dimethyl carbonate, and subsequent reaction with a fatty acid. In the process to make the quaternary amidoamine detergents a multifunctional fatty acid is reacted with an amino amine, typically an amino alkylene amine, followed by quaternization with a quaternizing agent and subsequent replacement of the anion of said quaternizing agent with a fatty acid anion. The quaternary fatty amidoamine detergents are particularly useful as a surface-active compound that is soluble in an a-polar medium, for example when used as a stabilizer for solids in an a-polar medium.