ZDDP is a critical additive to protect flat tappet camshafts and lifters from excessive wear and tear. It creates an anti-wear layer at friction points to eliminate metal-to-metal contact and heat. It is especially important in engine break-in where a new camshaft and lifters are experiencing extreme pressures and temperatures. Most modern oil formulas have significantly reduced levels of this important lubricant due to concerns about the impact on catalytic converter performance and to meet EPA emissions standards.
The technical name for znddp is Zinc Dialkyl Dithiophosphate but many people simply call it “zinc.” It is an extremely effective metal-to-metal anti-wear additive that’s also a great corrosion inhibitor. The chemical is created when a metal is heated, creating a thin film called a tribofilm that coats the moving parts. It’s most beneficial to flat tappet camshafts and valvetrain components but also benefits cylinder walls, piston rings and bearings.
During operation, the camshaft and lifters are subject to tremendous pressures and temperatures, which can rupture the oil’s protective barrier and lead to metal-to-metal contact. The tribofilm formed by znddp prevents this wear and extends the life of the camshaft, lifters and pushrods.
Most camshaft and valvetrain manufacturers recommend using an oil with more than 1000 ppm of ZDDP for engine break-in to achieve maximum horsepower and longevity. Some manufacturers even void warranties on new camshafts and crate engines if this level is not met during break-in.