Diesel additive for lubricity became essential with the introduction of ultra-low sulfur diesel (ULSD) regulations. The hydrotreating process used to remove sulfur from diesel also removes naturally occurring lubricating compounds. This results in diesel fuel with poor inherent lubricity, which causes excessive wear in fuel system components—particularly in modern high-pressure systems with tighter tolerances. Diesel fuel lubricity additives restore the lubricating properties that were lost during sulfur removal, preventing premature failure of expensive fuel pumps and injectors. While motor oil additives lubricants protect engine internals, specialized diesel fuel lubrication additive is needed to protect the fuel delivery system.

The best diesel additive for lubricity combines several key attributes: First, it should provide excellent lubricity enhancement as measured by standardized tests like HFRR (achieving wear scars well below the 520μm limit, ideally 460μm or lower). Second, it should offer additional benefits beyond just lubricity—such as detergency to clean injectors, cetane improvement for better combustion, and water control. Third, it should be compatible with all diesel types including ULSD, biodiesel blends, and renewable diesel. Fourth, it should be properly concentrated so that effective treatment requires reasonable dosages. Finally, the best diesel additive for lubricity should come from a reputable manufacturer with technical data to support performance claims, unlike some engine lubricant additives that may make exaggerated promises without evidence.

Diesel fuel lubricity additives and motor oil additives lubricants serve completely different purposes and function in different parts of the engine. Diesel fuel lubricity additives are added to the fuel and specifically protect the fuel delivery system—injectors, pumps, and other components that come into contact with diesel fuel. They’re designed to work in the fuel itself and protect against the poor lubricity of modern ultra-low sulfur diesel. In contrast, motor oil additives lubricants are added to engine oil and protect the engine’s internal moving parts—pistons, rings, bearings, camshafts, etc. They’re formulated to work in the oil sump and protect against the different wear mechanisms in the crankcase. Both are important for comprehensive engine protection, but they address different systems with different chemical formulations and cannot be used interchangeably.

A high-quality diesel injector lubricant additive with strong detergent properties can sometimes improve the performance of mildly dirty or clogged injectors by cleaning deposits and restoring proper spray patterns. However, it cannot repair physically damaged or severely worn injectors. The primary role of diesel injector lubricant additive is preventive—to protect injectors from wear and keep them clean before problems develop. For existing significant injector issues, mechanical repair or replacement is usually necessary. After repair, consistent use of a good diesel fuel lubricity additive can help prevent recurrence of problems. Think of diesel injector lubricant additive as preventive medicine for your fuel system rather than a cure for existing serious conditions.