Reduced ZDDP and Wear Protection

What is ZDDP?


Zinc dialkyldithiophosphate (ZDDP) is the most commonly used anti-wear additive in motor oils.


It contains both zinc and phosphorus components that work together to provide anti-wear protection and minimize lubricant breakdown.  ZDDP also exhibits mild extreme-pressure protection.

Some motorists think that increased zinc content equals increased wear protection.  Although somewhat true, the statement can be misleading.  First, the mere presence of zinc doesn’t mean it is in the form of ZDDP.  In other forms, zinc offers additional oxidation protection but little wear protection.  Second, other factors influence the oil’s ability to control wear, such as its viscometrics and base stocks.

While zinc is important in protecting against wear, the greatest concern should be in using a well-balanced oil that is designed for its intended application.

How ZDDP Works:

As temperatures rise and surfaces come closer together, ZDDP decomposes, and the resulting chemistry protects critical metal surfaces.

When parts move during operation, any sliding or rolling motion takes place on top of or within the  ZDDP anti-wear film, which reduces the metal-to-metal contact.  This is especially important in modified engines with flat-tappet camshafts because the engine is creating more horsepower than it was designed for, which puts more stress on the engine.

High-tension valve springs, often used in racing applications, also increase the potential for cam wear and require additional ZDDP.  Without the protective film barrier provided by ZDDP, the cams and lifters wear from the force of operation, negatively affecting cam and valve operation.  Because most V-8 engines of the muscle car era came standard with flat-tappet cams, the problem is especially prevalent to classic-car and hot-rod owners.

Amsoil-Break-In-OilIn these applications, modern oils, such as AMSOIL synthetic motor oils, are capable of providing adequate wear protection after the engine has been broken in.  But due to variables like severity of service and level of modification, AMSOIL primarily recommends high-ZDDP oils in these applications, such as Z-ROD Synthetic Motor Oil (ZRF, ZRT) or DOMINATOR Synthectic Racing Oil (RD20, RD30, RD50, RD60).

When breaking in a rebuilt or high-performance engine, AMSOIL recommends AMSOIL Break-in Oil (BRK), which contains high levels of ZDDP for added wear protection.

As the debate over ZDDP levels and engine wear continues, many enthusiasts and engine builders will continue to seek out high-ZDDP specialty oils. 






Reduced ZDDP and Wear Protection


Article credits AMSOIL Dealer Edition June 2014


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