NOVELTY - Biodegradable carrier oil derived from at least a plant or animal source, is claimed.    USE - The biodegradable carrier oil is useful in a carrier oil composition; a fuel detergent additive package; gasoline composition; and in a method of reducing valve sticking in an engine combusting a fuel (claimed).    ADVANTAGE - The carrier oil is biodegradable. The carrier oil reduces the formation of engine deposits and/or improves the fuel economy (all claimed). The carrier oil protects the engine from wear. The carrier oil exhibits an ability to blend in higher concentrations without requiring vehicle modifications. The carrier oil improves or enhances the friction properties and the lubricating capacity of the combustion engine. The carrier oil exhibits improved or enhanced low temperature viscometric performance.    DETAILED DESCRIPTION - INDEPENDENT CLAIMS are included for:    (1) a fuel detergent additive package comprising a biodegradable carrier oil and a detergent comprising an amine-functionalized biodegradable carrier oil derived from at least a plant or animal source and/or a detergent not derived from at least a plant or animal source;    (2) a gasoline composition comprising a gasoline fuel, a detergent, and at least a hydrocarbon-containing biodegradable carrier oil;    (3) a method of reducing the formation of engine deposits and/or improving fuel economy, in an engine combusting a fuel, comprising combusting, in an engine, a fuel composition comprising a major amount of fuel with a boiling point of 15-400degrees C, a detergent, and the carrier oil;    (4) a method of reducing valve sticking in an engine combusting a fuel comprising combusting in an engine a fuel composition comprising a major amount of a fuel with a boiling point of 15-225degrees C, a detergent, and the carrier oil;    (5) a diesel composition comprising a diesel fuel, and a detergent derived from at least a plant or animal source; and    (6) a method of reducing the formation of engine deposits in an engine combusting a fuel, comprising combusting, in an engine, the diesel composition comprising a major amount of a diesel fuel with a boiling point of 150-400degrees C.