Using zinc in older engines is necessary for a smooth performance and a long engine life. But if you use too much zinc, it can also damage the engine. The amount of zinc has to be just right. So, how much zinc additive to add to oil and what are its effects?
It depends on the composition of the engine oil you’re already using. Some have small quantities of zinc while others don’t have any zinc at all. You’d want to be around 1400- 1500 ZDDP during the break-in period and 1200 ZDDP after that.
I have a dedicated section on how you can achieve this ZDDP level. Besides, you’ll also learn about the pros and cons of using zinc in your car. So, keep on reading to learn all about it in detail.
Table of Contents
What Is A Zinc Oil Additive?
Before I get into how much zinc additive you should add to your engine oil, you need to know more about zinc additive. It’s important that you understand what ZDDP is and how it works. Only then, you can make an informed decision on whether you even need to add ZDDP to your motor oil or not.
ZDDP or Zinc dialkyldithiophosphates is a compound that’s rich in Zinc and Phosphate. Besides it, ZDTP or Zinc dithiophosphate is also a common compound used in motor oil. It’ll be a long science class if I sit around and explain the difference between them.
But for our intents and purposes, we can consider them to be the same. Now, the main job of adding zinc to oil is to increase protection. From the early 1940s, Zinc has been used in oil to protect the engine from wearing out.
It’s still heavily used in racing vehicles to defend the parts that are under extreme pressure during high performance. The property of zinc helps it stick to the metal parts of the engine.
Zinc forms a coating around the metal parts in the engine. When there’s extreme pressure inside the engine, the zinc turns into a phosphorus glass. Because of that, the metal parts can glide over each other as opposed to rubbing on each other.
Zinc additives are particularly useful as they provide heat and respond to areas where there is too much friction. As the temperature inside the engine rises, the metal parts come close to each other. But the zinc also gets decomposed and it prevents the metals from damaging each other.
So, zinc reduces the chance of metal-to-metal contact that would normally happen and prevents the parts from getting damaged. But there’s a caveat to using zinc. If you use too much zinc in the engine oil, it can also damage the components. You have to use the right amount of zinc for your vehicle.
Why Is Zinc No Longer Added To Oil?
There was a time when zinc was directly added to engine oils. So, you didn’t need to use any zinc additives for engine protection. But high zinc motor oils are a thing of the past.
Engine oils with a high amount of zinc are still found in racing vehicles. But when it comes to cars for everyday use, it’s not common to find engine oils high in zinc. If zinc is so great, then why have manufacturers stopped putting it in engine oils?
It’s because everything has a consequence. While zinc is great at preventing engine wear, too much of it also has a bad effect on the engine. During the 1940s, only 300 PPM of zinc was generally used in engine oils.
Seeing the effectiveness of Zinc, its proportion kept increasing in engine oils. The amount of zinc went from 300 PPM to nearly 1400 PPM in most engine oils during the 1980s and 1990s. But then, disaster struck.
Hot rodders and car enthusiasts started noticing issues with their engines. It took a while but they eventually figured out that this issue was caused by the additional zinc. Oil manufacturers also understood that too much zinc in the engine oil would also harm the engine.
The main concern of using too much zinc is that it damages the catalytic converter in a car. The premature failure of the catalytic converters led to many issues for car manufacturers. That’s because they were required to last more than 100,000 miles as per government regulations.
But high zinc oils got in the way of that. So, eventually, all oil brands started pulling back on the amount of zinc and only a little zinc is used in engine oils. The common quantity of zinc you’d find in modern engine oils is around 800 PPM to 1000 PPM.
Zinc isn’t as important in roller cam engines as much as it is for flat tappet cam engines. I have a section on it if you want to check out the differences between them. But zinc is necessary for flat tappet engines and you have to make sure that you add the correct level of zinc to the engine oil.
How Much Zinc Additive To Add To Oil?
You need to use the right amount of zinc for your engine. If you use less or more than what’s required, your engine components will start wearing out. But don’t worry, I’ll walk you through how you can figure out the right amount of zinc for your car.
First of all, you don’t have to worry about adding zinc if you own a modern car. The engines in modern cars are built differently. They don’t require any more zinc than what you’d get with regular engine oils. Just make sure you use the right oil as per the instructions of your car manufacturer.
But when it comes to the older engines, they need the right amount of zinc. The minimum Zinc you’d require in flat tappet engines is 1000 PPM. But it’s better to have around 1200 PPM of Zinc to be on the safe side.
During the break-in period of the car, 1400- 1500 ZDDP for the first 500 miles is okay. If you have a car that has a catalytic converter, reduce the amount of ZDDP to 1000 PPM after the break-in period. If there’s no catalytic converter, you can reduce the amount of ZDDP down to 1200 PPM.
Now, how much ZDDP you need to add depends on how much ZDDP there already is in the oil you’re using. You need to know how much ZDDP there is in the oil and you can do it by looking at the label and API rating.
SH, SJ, and SL are some common oil engine oil ratings. SH is no longer continued but it used to have 1200 PPM ZDDP. In SJ-rated engine oils, the quantity of zinc came down to 1000 PPM.
Even that took a toll on the engines and SM-rated oil was brought out with a ZDDP composition of 800 PPM. Nowadays, the most common engine oil rating you’ll come across is the SN API rating. There are 600 to 700 PPM ZDDP in engine oils with an SN rating.
You can look at the API donut graphic that’s on the label of the engine oil. So, you should select an engine oil that’s close to your requirements. Then, you can top off the remaining bit with a small concentration of Zinc additives.
The other option is to choose an engine oil that has no zinc at all. Then, you can get the required amount of zinc from the additives. The main thing here is to know how much zinc your vehicle needs and create a system to get it.
That’s how easy it is to calculate and get the zinc required for your car. Hopefully, now you know how much ZDDP is enough and how much ZDDP is too much. I already told you about the right levels based on your engine.
Keep in mind that adding too much Zinc is just as harmful as not having enough. So, maintain the right level of Zinc to prevent engine wear and keep your vehicle performing well.
What Are The Benefits Of Using Zinc In Engine Oils?
There are two main benefits to using engine oils that are high in zinc. These two benefits are so significant that they make hot rodders use zinc oil every time. Let’s take a quick look at them.
i). Engine Protection
A zinc additive is a polar substance that reacts to the polar compounds or materials of the engine. So, zinc naturally gets attracted to the iron and metal components of the engine.
Because of that attraction, the zinc moves from the engine oil to the metal surface. It also forms a thin protective layer on the metal surfaces. That protective layer makes all the difference when the engine is under heavy load.
The zinc additive keeps the different metal parts from rubbing on each other. Otherwise, the metal components would get damaged and start wearing out soon. So, that’s zinc additives protect the engine.
ii). Oxidation Inhibition
The molecules of the engine oil react with the oxygen. Eventually, that causes corrosion of the engine components. So, this process of oxidation is harmful to the engine and it also reduces the lifespan of the engine.
Luckily, zinc also helps prevent this issue to a large degree. Zinc is an oxidation inhibitor by nature and it will make the process of oxidation much slower. So, zinc additives help keep the engine safe in the long run.
Without zinc, you’d have to change the lubricant or the engine oil more frequently. That’s because oxidation depletes the molecules of the engine oil. But when you add zinc, even the lubricant will last longer.
What Are The Disadvantages Of Using High Zinc Motor Oil?
If zinc was great, then oil manufacturers would have never stopped adding it to the engine oil. But most standard engine oils don’t have zinc anymore. And that’s also for good reason.
Using zinc in engine oil hasn’t exactly been all rainbows and butterflies. During the 1990s, the amount of ZDDP in motor oil was at its peak. Car enthusiasts and hot rodders started noticing issues with their vehicles.
The main downside to using oil with high ZDDP was that it had an adverse effect on the catalytic converter. There’s a mesh coated in platinum inside a catalytic converter. The zinc in oil would react to it and reduce the efficiency of the catalytic converters.
However there were regulations on the catalytic converters. They needed to work properly to reduce the carbon emissions on the environment. So, the quantity of zinc was gradually decreased in engine oil.
Besides, engines with roller camshafts also came into action during that time. They didn’t need zinc as much as their flat tappet counterparts. So, the need for zinc got even more reduced. That’s why zinc is rarely found in modern engine oils unless you actively seek it out.
Why Do You Need Zinc For Flat Tappet Cams?
I’ve already told you that zinc is mostly necessary only for older engines. Especially, the cars that were made before the 1980s. In this section, I’ll get into this topic deeper and explain the reason behind it.
The main reason that you’d have to zinc in older cars is because of the engine design. Most vehicles manufactured before the 1980s utilized a flat tappet camshaft. These flat tappets create a lot of friction.
The cam lob slides on the tappet consistently. It raises the temperature inside the engine and generates a good deal of friction. If you don’t apply proper lubrication to such an engine, the metal parts will rub against each other. So, the engine will end up being damaged.
That’s exactly where the zinc comes into play. Zinc reduces the amount of friction and keeps the metal parts from breaking down. The metal components will glide over each other instead of rubbing on each other due to zinc.
But then, why is zinc not needed in modern cars? Because most vehicles made after 1989 use roller cam designs. There’s a lot less friction in such designs and that’s why zinc isn’t necessary in those cars.
Hopefully, everything is clear to you by now and you realize why you need zinc in older cars. If you have a car that was made before 1989 and uses a V6 or V8 engine, you’ll require zinc in the engine oil in your car.
But the problem is that most standard oils don’t have the required zinc for your car. So, you have to turn your attention to the zinc additives. So, follow the instructions of the zinc supplement you use when adding it. Make sure you strike the right balance of zinc so that the engine runs smoothly.
Do You Need Zinc Additives For Engine Break-In?
The break-in period is arguably the most important stage for freshly built engines. The pattern set here sets the engines up for the rest of their lifetime operation. The lifters in the flat tappet cams are worked and their wear pattern is set right from the break-in period.
Adding ZDDP during this time helps the lifter break by helping the spinning action of the camshaft. If the ZDDP doesn’t create this traction, the lifters will not wear out eventually. So, a cam lobe would go bad quickly.
According to Speedmotors, “All new engines, regardless of year or cam style, require ZDDP for the first start-up and break-in period. This is for crate engines, rebuilds, and new custom builds”.
That’s why it’s so important to use zinc for the break-in period of engines. You can use a prepackaged ZDDP additive for the first 500-1000 miles. Once that period passes, you can just add the zinc additive after every oil change.
Adding zinc additives helps all types of engines during the break-in period. Even modern engines require zinc additives during the break-in period. However, they don’t need as much as the flat tappet cams. Using 1400 – 1500 PPM of ZDDP during break-in is enough for modern engines.
Should You Choose High Zinc Motor Oil Or Zinc Replacement Additives?
High zinc motor oils aren’t common these days. They already have a good amount of ZDDP in them. But another option for you is adding zinc additives to the engine oil you’re using. The main question is which of these two would be the better option for you.
Using zinc in oil was stopped because of the damage they do to the catalytic converters. Though the safety of the environment and catalytic cars is essential, older engines can’t run without zinc.
That’s where the zinc replacement additives come into action. They’re a good choice as they give you the benefits of engine protection in high-performance vehicles. However, they don’t have as much of an adverse effect of using motor oils that are high in zinc.
Here are the main benefits of using zinc additives compared to motor oil that’s rich in zinc:
i). Better Engine Protection
If you choose the right zinc additive, it’ll offer better protection than ZDDP-based engine oils. So, you can expect your engine to last longer if you use zinc additives instead of oils that are rich in zinc.
ii). More Environment Friendly
One of the biggest problems with engine oils high in ZDDP is that they damage the catalytic converter. Moreover, the emissions that come from using this type of oil are also more harmful to the environment.
However, you can avoid these issues by using a zinc additive to your regular engine oil. A good zinc additive won’t damage the catalytic converter and it’ll increase the lifespan of the engine. On top of that, the emissions that come from using zinc additives aren’t as high as using a high zinc oil.
iii). Cold Start Protection
The vehicles inactive for a while are at risk of getting damaged due to a cold start. But the risk of engine damage will be reduced greatly if you add zinc additive to your engine oil.
Overall, using a zinc additive is a better option than using a high zinc motor oil for most vehicles in my opinion. But if you’re thinking of racing or you have other applications in mind, a high-zinc motor oil could be the way to go.
Rather than relying on a brand, it’s important that you understand your needs first. Then, you need to select the engine oil based on that. Here’s our list of top high-zinc motor oils if you’re interested to know more about them.
Do You Need Zinc Additive For Synthetic Oil?
The main difference between synthetic oil and regular oil is that there are fewer impurities in synthetic oil. So, they lubricate the internal components better and give a smoother performance.
But that still doesn’t change the fact that modern engine oils don’t have enough zinc. Regardless of whether you have regular engine oil or synthetic oil, it won’t have the minimum zinc for older engines.
You don’t need zinc in your oil if you have a modern car. But you’d have to add a zinc additive to the engine oil for older vehicles. If synthetic oil is too expensive, you can also opt for a semi-synthetic oil. It’ll still give a smoother engine performance than your regular engine oil.
What Is The Best Zinc Additive For Engine Oil?
Zinc additives are great for older engines. But you need the right zinc supplement to protect your car’s engine at all times. In my opinion, you can’t go wrong with the Rislone Hy-per Lube ZDDP Supplement as an additive to your engine oil.
It has a great formulation and the right mix of zinc and phosphorus to protect older engines. The end result is that you’ll have a cooler engine with minimum friction. The additive will also prevent the viscosity and thermal breakdown of the engine oil and stabilize it.
You can make the newer oils work in older cars with this zinc additive. While normal oils don’t protect older engines, the clinging action of zinc will protect the internal bearings. So, you should consider this Rislone zinc additive for the well-being of your car’s engine.
How much zinc additive to add to oil and what are its effects? Hopefully, you know all about it now after completing this guide. If you have a car with an older engine, adding zinc to oil is a must.
But it’s not a necessity for modern engines. They’ll run just fine without adding any zinc to them. So, only use zinc oil for older engines. Make sure you maintain the right amount of zinc to ensure the optimal performance of your car engine.