Most hot rodders and classic car owners spend a lot of time and money to maintain their ride. They want to make sure it runs like the day they drove it off the dealer's lot, and that their investment is well-protected. That's why they choose motor oil with zinc for older cars.
motor oil with zinc for older cars contains higher concentrations of ZDDP or ZDTP (Zinc Dialkyl Dithiophosphates) than standard motor oils. These additives bond to metal parts of the engine, creating an anti-wear coating that prevents them from rubbing together. They are commonly used in older engines with flat tappet camshafts, which generate a lot of friction.
Zinc can also be found in other types of additives, such as boron and molybdenum, which are often added to conventional motor oil to improve its lubrication qualities. These ingredients are called "zinc-based additives," but many people who use the term simply refer to the compound known as zinc dialkyl dithiophosphates, or ZDDP, which is an excellent lubricant.
In recent years, however, the EPA and OEM engine manufacturers have directed companies to reduce the amount of ZDDP in their products. This is because the compound can interfere with catalytic converters and cause them to wear down more quickly than they otherwise would. As a result, the high-zinc additives that were common in older engines have disappeared from most standard motor oil formulations. However, there are a few companies that still produce oil with the high levels of ZDDP needed by classic car enthusiasts.