A method for reducing the formation of combustion chamber deposits in an engine using a friction modifier for combustible fuels is provided. The friction modifier is prepared by combining a saturated carboxylic acid and an alkylated or alkoxylated amine. The particular selection of friction modifier enables a stable additive concentrate to be formulated providing a significant decrease in CCD without increasing the incidence of IVD deposits in combustion engines running on a fuel modified with the additive concentrate.