About ZDDP
Zinc dialkyldithiophosphate (ZDDP) is a powerful sacrificial anti-wear additive. This chemical binds to metal surfaces under high pressure, creating a protective coating that prevents wear.
ZDDP is the main component in many lubricants, and it’s found in premium engine oils. It’s also a corrosion inhibitor that helps keep expensive components in the engine from rusting away.
In most cases, modern motor oil with reduced levels of ZDDP is adequate for older pushrod engines with flat tappet cams, but some classic car and hot rod owners will want a higher level of protection. They need to protect their cylinder heads, bearings, lifters and pushrods from the grit and debris of road salt, abrasive dust, and dirt particles that can get into the engine oil.
During engine break-in, these components are exposed to huge amounts of heat and pressure. This is where a good quality ZDDP supplement or a motor oil formulated with a higher amount of ZDDP comes in handy.
When a motor oil contains too much ZDDP, it can increase friction and wear between the camshaft lobes and the lifters that press against them. In addition, too much ZDDP can lead to carbon buildup in the valve train and in the exhaust cylinder walls that could prematurely clog or damage catalytic converters.
The good news is that the industry is gradually moving toward more natural oil formulations, where zinc and phosphorus are added in small amounts to provide antiwear and corrosion protection. These products are a better fit for classic and hot rod engines, because they allow the engine oil to work as it should, and they don’t create emissions that would prematurely destroy catalytic converters.