An additive composition comprises at least one colloidal metal compound or metallic species and a stabilising component, wherein the stabilising component comprises the product obtainable by the condensation reaction between: (i) at least one aldehyde or ketone or reactive equivalent thereof, and (ii) at least one compound comprising one or more aromatic moieties bearing at least one hydroxyl group and at least one further substituent chosen from a hydrocarbyl group, —COOR1 or COR1, wherein R1 represents hydrogen or a hydrocarbyl group. The composition may further include at least one lubricity enhancer. Compositions of the invention tend to resist haziness, cloudiness and phase separation at relatively low and relatively high temperatures, and in the presence of lubricity enhancers and fatty acid methyl esters (FAME).