Chances are your classic car needs zinc oil additive to stay running strong. While the formulations of modern oils have changed, along with the innovations that keep the automotive industry moving forward, your older car’s specific lubrication requirements were frozen in time the day it was built. This means that not all current oils are appropriate for antique autos — or even for those built a few decades ago.
Let’s take a quick look at how zinc in your oil can impact your engine.
Before the 1980s, most engines were outfitted with a camshaft design that used “flat tappets,” which generated more friction than later, roller-cam designs. If left unprotected, this friction can generate damaging levels of heat, and also wear down a cam so much that performance and efficiency are negatively affected.
This wasn’t an issue back in the day, because oil manufacturers employed additives called ZDDP and ZDTP, which used zinc and phosphorus, respectively. Together, these heat-activated additives provided protection for hot spots on a cam where metal-on-metal friction was at its maximum. But they were gradually removed from lubricants as tech changed, which means that modern oils aren’t always as good at providing an effective barrier in certain older motors.
Fortunately, there are several oil companies that have recognized the need for motor oils that address the concerns of owners with flat tappet camshafts in their cars. Zinc oil additive content, or ZDDP, is typically expressed in parts per million (ppm). To meet the standards required to protect an older motor, you’ll want to look for a ZDDP level of between 1,000 ppm and 1,400 ppm, with a similar rating for ZDTP phosphorus content.
As a side note: Many engine builders also recommend high levels of zinc oil additive during the break-in period for a new motor. Some crate engines and fresh builds push ZDDP to 2,000 ppm during the first 500 miles of use when the engine is most vulnerable to uneven wear.
Isn’t it worth using the oil that your engine was originally designed for? Make sure to investigate zinc oil additive in your vehicle’s lubrication options before committing to a specific brand. You’ll be grateful when your classic car keeps running smoothly.
Check out all the chemical products available on NAPA Online or trust one of our 17,000 NAPA AutoCare locations for routine maintenance and repairs. For more information on zinc oil additive, chat with a knowledgeable expert at your local NAPA AUTO PARTS store.
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Having been bitten by the car bug at a young age, I spent my formative years surrounded by Studebakers at car shows across Quebec and the northeastern United States. Over ten years of racing, restoring, and obsessing over automobiles lead me to balance science writing and automotive journalism full time. I currently contribute as an editor to several online and print automotive publications, and I also write and consult for the pharmaceutical and medical device industry.