As an owner of a classic car, hot rod, or vintage truck; you want the best, and zinc oil additive are the types of products that will help you give your classic car engine the best protection possible.
Almost everyone who’s into cars has an older vehicle that they love. Whether it’s the feeling that they get behind the wheel or the way the car looks parked in their driveway, they pour their time and effort into maintaining the car and keeping it looking like it’s just been driven off the lot.
There are numerous positive effects of zinc oil additive on older engines, especially those with flat-tappet camshafts. The more you know about the need for anti-wear protection and a zinc oil additive for old cars, the more you’ll realize that you can’t just go with any old motor oil on the shelves today.
Instead, you’ll need to look for motor oil that provides the same protection that motor oil with zinc for older cars provides, without the negative effects that come with high zinc products. Instead of going with high-zinc motor oil or an oil that’s used for more modern cars, you’ll likely want to go with a zinc replacement additive, which will provide you with the wear protection you need without the adverse effects of zinc products.
Before you decide on whether to use a replacement zinc oil additive or stick to classic zinc formulated motor oil, you’ll want to know all the facts about high-zinc motor oils, the effects of zinc additive on old engines and how zinc replacement additives work.
What Is High-Zinc Motor Oil?
whenever friction becomes an issue. To reduce the added strain on the motor produced by the friction and heat that comes with it, many older car owners choose high-zinc motor oil.
The high zinc content is especially useful for cars that are regularly under strain due to temperature change, harsh road conditions, consistently driving at high speeds and pushing your vehicle to its limits, among other straining factors. In situations where the vehicle is under strain, the zinc contents of the oil offer higher heat resistance and reduced oxidation. These features help car engines last longer and improve their overall capabilities.
The primary role of motor oil with zinc added to it is to ensure that there is no metal-to-metal contact occurring between parts of your engine. The oil accomplishes this by creating a protective film between parts. As it does the job so well, it’s often used in high-performance racing cars and other off road sport vehicles. Due to the engine design of older vehicles, it’s also a popular option for older vehicles with flat tappet camshafts.
How Do Zinc Additives Work?
The “zinc” in motor oil is often shorthand for zinc dialkyl dithiophosphates, a compound, otherwise known as ZDDP. At times, zinc can also refer to zinc dithiophosphate (ZDTP), which is a phosphorous ingredient often paired with ZDDP for superior protection. Instead of having to say all of that, people in the industry simply refer to ZDDP as zinc.
Both ZDDP and ZDTP have been used as anti-wear ingredients for many years in the formulation of motor oils. When zinc and phosphorous ingredients are paired together, they provide the highest level of protection. The effect of the combinations makes ZDDP and ZDTP a natural pairing for anti-wear oils.
Zinc oil additive work by responding to heat and providing protection for areas where there is a great deal of potentially damaging friction. When the temperature rises and different metal surfaces in the engine start to come closer to one another, ZDDP decomposes due to the heat. This decomposition creates a chemical reaction that protects the metal surfaces of the engine from becoming damaged.
As engine parts move during the vehicle’s operation, the rolling or sliding motions of the machinery occur within or on top of the ZDDP anti-wear film. This film then reduces the amount of metal-to-metal contact that occurs during the vehicle operation, reducing wear and tear on the engine. For engines that are designed to generate a great deal of horsepower or that have flat tappet camshafts, the usage of the zinc-containing motor oil is crucial.
Oil testing done on older car engines has found that there is a brief period when the engine is just warming up when it needs to have more lubrication than modern-day, non-zinc motor oil provides. In this start-up period, a non-zinc oil typically won’t provide the needed amount of lubrication to keep metal off metal. The proper oils for these engines will often have increased amounts of ZDDP/ZDTP.
How Do Zinc Additives Affect Old Engines?
If your older vehicle has an engine that uses a flat tappet lifter, it will need to have zinc or a zinc replacement additive in its engine oil. Having zinc in the engine oil will prevent the lifters and camshaft from wearing down prematurely. If your vehicle uses a V6 or V8 engine made before 1988, it’s highly likely that it will have been designed to have zinc in the engine oil.
When you look at engines manufactured before the 1980s, you’ll find that most had a camshaft design that utilized flat tappets. The flat tappets in these engines create a significant amount of friction. Later roller cam designs would reduce this friction. Still, if you’re driving an older car, you’re likely using a camshaft designed engine outfitted with flat tappets, making the use of zinc oil additives crucial.
When a flat tappet engine is left without any protection, the friction generated can do a great deal of damage to it. For example, the heat generated by the friction can harm the engine. Along with the heat, the friction can harm the efficiency and the performance of the engine by wearing down the cam.
While there were plenty of motor oils that had zinc additives in them, as engine technology evolved, and new engines became standard, modern oil companies began to produce oil without ZDDP or ZDTP. Now, most standard motor oils do not have any zinc additives in them. As such, it’s often not wise to use modern oils for classic engines, and you’ll usually only see zinc in oil for old cars.
Though zinc additives have gone out of fashion with newer engines, there are still companies that produce them or replacements of them. As you shop for motor oils, you’ll not want to pick the first one you see off the shelf. Instead, you’ll need to find motor oil that has appropriate levels of ZDDP and ZDTP or that has formulated a specialized zinc replacement that provides the same or better levels of protection.
Typically, ZDDP and ZDTP are described in parts per million (ppm). If you’re set on selecting a zinc oil, you should look to see if the ZDDP level is somewhere between 1,000 ppm and 1,400 ppm. For ZDTP, you’ll want to check to see that the phosphorous content is in a similar range as well.
Potential Downsides to Zinc Additives
If zinc additives help older cars run properly, you might be wondering why the industry wouldn’t just stick with the formula and keep the zinc levels the same. However, people found that zinc can harm the engine. When researchers investigated the effects of zinc, they found that a small amount of motor oil would find its way into the engine’s combustion chamber. In this chamber, the zinc in the oil would become ash before being transferred through the exhaust pipe.
After it had moved through the exhaust pipe, the zinc ash would sometimes come to rest on a catalytic converter. Over time, this ash caused harm to the converter, reducing its effectiveness gradually. This zinc ash can harm the engine’s lifespan, forcing you to pay extra money to repair or replace the engine if you don’t keep a close watch on it. Along with harming the catalytic converter, the phosphorous in a zinc additive can produce carbon buildup in an engine’s valvetrains or bores.
Today, most motor oils have reduced the amount of zinc they use dramatically. In place of zinc, they’ve added more boron to their oils as a replacement but have not been able to maintain the same quality. This change to non-zinc oil comes with its own downsides, as a non-zinc oil made for modern engines doesn’t offer the same level of dry start protection as motor oil using zinc for older engines.
Due to the problems associated with zinc, most motor oil companies will not include any zinc in their formula to protect against damage to the catalytic converter in newer engines. If you’re set on using zinc, you’ll want to check to see if it’s in the 1,000 to 1,400 range mentioned previously. However, older vehicles still need to use the heavy-duty, anti-wear protection of zinc to prevent more significant adverse effects.
Stay tuned in Part 2 as we will discuss why you may want to use Zinc oil additive in your classic car engine.
I have a 1967 Mustang with the 289 engine and I want to know if using a Zinc additive will be a good thing for this classic or will it harm it.
Also, I did buy a bottle of Zinc and I notice that it is a very thick liquid.
If I do add this to the engine that holds 5 quarts of oil with the filter how much zinc would I add?
Thanks for your help.
Bob:
In general, I use Zinc in conventional oil and not with synthetic oil. I am not aware of any issues in the regular use of zinc in oil since it is a supplement lubricant for engines. I use regularly in both my Ford and Chevy engines.
I add a full container of zinc additive when I change the engine oil, so when doing an oil/filer change I fill the oil filter before installing onto the engine then add 4 – 4 1/2 quarts (or 1-1 1/2 quarters shy of the full requirement depending on the oil pan size) into the engine with the zinc. I run the engine to check for leaks and then recheck the oil level in the engine to add any additional oil. This method avoids any chance of overfilling the engine oil.
I hope that answers your questions.
Thanks for asking and reading our blog.
Bob