Abstract: A water in oil emulsion having 70 to 99 wt % diesel fuel the diesel fuel having 0 to 50 vol % biodiesel blended fuel, 0.5 to 30 wt % water, 0.01 to 5 wt % alkyl amine ethoxylate at least 25 wt % of the alkyl amine ethoxylate being C10 to C14 alkyl amine ethoxylate and at least 25 wt % of the alkyl amine ethoxylate being C16 to C18 alkyl amine ethoxylate and 0.03 to 1 wt % of the product obtainable by reacting a polyisobutylene succinic anhydride of molecular weight 9000 to 2600 with 1 to 2 moles of a tertiary alkanol amine. The emulsion is stable and is useful as a biodiesel blended fuel.