Zinc Versus Detergent In Motor Oil

While the reduction of zinc, phosphorus and sulfur in today’s motor oils is a significant change, there is more to the story. Specifically, the detergent additives used in modern oils have also changed. Here are some key facts about zinc and detergents and how they work.


The oil additive Zinc DialkylDithioPhosphate (ZDDP) works because it is a polar molecule, so it is attracted to ferrous metal surfaces. However, Zinc (ZDDP) is not a lubricant until heat and load are applied. ZDDP must react with heat and load to create the sacrificial film that allows ZDDP to protect flat-tappet camshafts and other highly loaded engine parts. The Society of Automotive Engineers’ Automotive Lubricants Reference Book states,“ZDDP is the predominant anti-wear additive used in crankcase oils, although it is a class of additive rather than one particular chemical..” Not all ZDDP additives are the same. Some zinc additives have slower “burn” rates that require more heat and more load to activate than other zinc additives. As a result, not all “High Zinc” oils have the same activation rate. The Driven BR Break-In oil uses a “Fast Burn” ZDDP that activates quickly.


Detergents and dispersants in the oil complicate the situation. Detergent and dispersant additives “compete” against zinc in the engine because they are polar molecules as well. Detergents and dispersants clean the engine, but they don’t distinguish between sludge, varnish and zinc – they clean all three away. Modern API certified oils contain higher levels of detergents and dispersants due to the exhaust gas recirculation (EGR) systems on passenger cars and diesel trucks. The “old school” theory on engine break-in was to run non-detergent oils, and this allowed for greater activation of the zinc additive in the oil.

Driven BR Break-In oils utilize the correct balance of anti-wear additives and detergents, so you don’t need to buy expensive additives to try to “fix” a low zinc (ZDDP) oil.