A diesel fuel composition containing metallic additives that are stabilised against phase separation. The diesel fuel contains a colloidally dispersed or solubilised metal catalyst compound, which can be used for diesel particulate trap regeneration and, as a stabiliser, 5-1,000 ppm (weight) of an oil-soluble or oil-dispersible organic compound having a lipophilic hydrocarbyl chain having attached directly thereto at least two contiguous polar head functional groups, i.e., the functional groups are separated by no more than three carbon atoms. The diesel fuel composition is particularly suitable for use with diesel engines fitted with a particulate trap for emissions control.