Why use high zinc motor oil? ZDDPs Explained

As a classic car enthusiast or high-performance engine owner, you've likely heard about high zinc motor oils. But why are they so important, and why should you consider using them? As a former Ford Motor Company Engineer and current AMSOIL Regency Platinum 12-Star Direct Jobber, I've spent years working with various engines and lubricants, recommending the right oils to hundreds of customers and retailers, as well as deciding on the best oils for my vehicles, equipment, and machinery. Today, I'm going to share my knowledge about high zinc motor oils and why they might be crucial for your engine.

Understanding ZDDP (Zinc Dialkyldithiophosphate)

At the heart of high zinc motor oils is a compound called ZDDP (Zinc Dialkyldithiophosphate). ZDDP is a powerful anti-wear additive that's been used in motor oils for decades. It works by forming a protective layer on metal surfaces, particularly in areas of high pressure and temperature within your engine. This layer acts as a heat-activated, sacrificial barrier, preventing metal-to-metal contact and reducing wear especially in high-friction environments.

ZDDP additives are heat-activated, meaning they provide wear protection in areas of increased friction. As temperatures rise and surfaces come closer together, ZDDP decomposes and the resulting chemistry protects critical metal surfaces. When parts move during operation, any sliding or rolling motion takes place on top of or within the ZDDP anti-wear film, which reduces metal-to-metal contact.

The Benefits of High Zinc Motor Oil

High zinc motor oils offer several key benefits:

1. Enhanced wear protection: The higher concentration of ZDDP provides superior protection against wear, especially in engines with flat-tappet camshafts.
2. Improved performance in older engines: Classic engines were designed with these higher zinc levels in mind, and using a high zinc oil can help maintain their performance and longevity.
3. Protection for engines with flat-tappet camshafts: These components are particularly vulnerable to wear and benefit significantly from the added protection of high zinc oils.

When to Use High Zinc Motor Oil

High zinc motor oils are particularly beneficial for:

1. Classic cars and vintage engines: These older designs often require higher levels of zinc for proper protection.
2. High-performance and racing applications: The extreme conditions in these engines benefit from the added wear protection.
3. Engines with flat-tappet camshafts: These components are especially reliant on the protective layer formed by ZDDP.

The Evolution of Motor Oil Formulations

In recent years, zinc levels in motor oils have been reduced to protect catalytic converters in modern vehicles. While this change benefits newer cars, it has left owners of classic and high-performance engines searching for alternatives. This is where specialized high zinc oils, like AMSOIL Z-Rod, come into play. High zinc motor oil formulations are particularly beneficial in engines utilizing flat-tappet lifters.

It's important to understand the difference between flat-tappet and roller cams. Flat-tappet cams, common in classic V-8 engines, are more vulnerable to wear due to their design. The cam-lobe slides rapidly over the flat tappet, increasing friction and temperatures. A thin oil film is the only barrier preventing wear, making high-zinc oils crucial for these engines. Roller cams, found in most modern vehicles, have rolling contact rather than sliding contact, reducing the need for high-zinc oils.

FAQs About High Zinc Motor Oils

As an AMSOIL Dealer and former Ford Engineer, I often get questions about high zinc motor oils. Here are some of the most common:

What does high zinc do to an engine?

High zinc content forms a protective layer on metal surfaces, reducing friction and wear. This is particularly important for engines with flat-tappet camshafts and other high-pressure contact points.

Is ZDDP good for your engine?

Yes, especially for older engines or high-performance applications. ZDDP offers superior anti-wear protection and helps extend engine life in vehicles designed for higher zinc content oils. However high ZDDP levels can reduce the performance of catalytic converters, so double check your vehicle's service manual to ensure the OEM doesn't prohibit the use of high zinc engine oils.

How much zinc should be in engine oil?

For older engines or high-performance applications, zinc levels should typically be around 1200-1500 parts per million (ppm). AMSOIL Z-Rod, for example, contains over 1400 ppm of zinc. For break-in, AMSOIL Break-In Oil contains even higher levels: 2,200 ppm zinc and 2,000 ppm phosphorus. After break-in, it's recommended to use an oil with at least 1,000 ppm ZDDP in a flat-tappet engine for optimal protection.

Is zinc good for small engines?

While beneficial for wear protection, most modern small engines don't require high-zinc oils. However, for older or high-performance small engines, a high-zinc oil can be beneficial.

Can you have too much zinc in oil?

While zinc is beneficial, excessive amounts can potentially harm catalytic converters in modern vehicles. That's why it's crucial to use high-zinc oils only in recommended applications, typically older or high-performance engines.

AMSOIL Z-Rod: A Solution for Classic and High-Performance Engines

As an AMSOIL Dealer, I've seen firsthand the benefits of AMSOIL Z-Rod for classic and high-performance engines. Here's why it stands out:

Features of AMSOIL Z-Rod

• Z-Rod is specifically formulated to protect engines in classic and high-performance vehicles. It provides robust anti-wear protection and helps prevent rust during long-term storage.
• AMSOIL Z-Rod contains over 1400 ppm of zinc, meeting the needs of engines designed for high-zinc oils.
• Z-Rod not only protects your engine during operation but also during storage periods, making it ideal for seasonal vehicles or show cars.

Best Practices for Using High Zinc Motor Oils

To get the most out of high zinc motor oils:

1. Choose the right oil for your engine: Consult your vehicle's manual or a trusted expert to ensure you're using the appropriate oil for your specific engine.
2. Follow recommended oil change intervals: While high zinc oils offer superior protection, they still need to be changed regularly. Follow the manufacturer's recommendations or consider oil analysis to determine the optimal change interval.
3. Be aware of potential impacts on catalytic converters: If your classic car has a catalytic converter, be mindful that long-term use of high zinc oils could potentially affect its performance.

As we've explored, high zinc motor oils play a crucial role in protecting classic and high-performance engines. The higher concentration of ZDDP provides the necessary wear protection these engines need, particularly for components like flat-tappet camshafts that are prone to wear.

From my years of experience both as a Ford Engineer and an AMSOIL Dealer, I can confidently say that using the right oil makes a significant difference in your engine's performance and longevity. For owners of classic cars, hot rods, or high-performance vehicles, a high zinc oil like AMSOIL Z-Rod can be the key to maintaining your engine's health and performance.

Remember, while high zinc oils are essential for certain applications, they're not necessary or even recommended for all engines. Modern vehicles with catalytic converters are designed to work with lower zinc content oils. Always consult your vehicle's manual or a trusted expert to determine the best oil for your specific engine.

Ultimately, the goal is to match the right oil to the right engine. By understanding the role of zinc in motor oil and the needs of your particular engine, you can make an informed decision that will help keep your cherished vehicle running smoothly for years to come.

Whether you're preserving a piece of automotive history or pushing the limits of performance, choosing the right high zinc motor oil is an investment in your engine's future. And as always, if you have any questions about which oil is right for your vehicle, don't hesitate to reach out to a knowledgeable AMSOIL Dealer like myself. We're here to help you get the most out of your engine, no matter its age or application.