A fuel oil composition comprising a major amount of a fuel oil and a minor amount of a compound being the product of the 1,4-addition reaction of (i) ammonia, a primary or secondary hydrocarbyl-substituted amine or a mixture thereof to (ii) a species containing one or more α,β-unsaturated carbonyl groups, wherein the compound includes at least one hydrocarbyl group containing at least 10 carbon atoms. The fuel oil composition has improved low temperature properties.