High Zinc Oil AMSOIL

There has been a lot of  buzz lately in the classic car and hot rod scene regarding the amount or lack there of zinc in motor oil.

The American Petroleum Institute (API) and International Lubricants Standards Approval Committee (ILSAC) have mandated the reduction of phosphorus to extend catalytic converter life.  However, reducing the level of ZDDP can compromise protection to engine components, most notably in flat tappet camshafts.  Current API SN and ILSAC GF-5 specs for gasoline engines have maximum and minimum phosphorus levels of 800 ppm and 600 ppm, respectively, for SAE 0W-20, SAE 5W-20, SAE 0W-30,
SAE 5W-30 and SAE 10W-30 motor oils.

What is zinc as it refers to motor oil? Really there are two compounds. Zinc and Phosphorus. Most people refer to zinc but they should not forget that phosphorus plays an important role in the formation of ZDDP. Zinc- dialkyldithiophosphates (often referred to as ZDDP) is used as an anti-wear additive and added to lubricants such as greases, gear oils, and motor oils, which contain about 1% (1000-1400 ppm).

If you have a hot rod or an older car you may be compromising wear if you use any of the newer specification motor oils. Reduced ZDDP oils have been cited as causing damage to, or failure of, classic/collector car as well as motorcycles camshafts and lifters with flat tappets which undergo very high boundary layer pressures and/or shear forces at their contact faces, and in other regions such as big-end/main bearings, and piston rings and pins. ZDDP compounds also serve as corrosion inhibitors and antioxidants.

The good news is that AMSOIL has several products in the line up that have plenty of zinc (ZDDP) for optimum performance in racing, classic cars and hot rods. This also applies to high performance motorcycles that have high lift cams, namely Stoker Harley Davidson type bikes. Though most motorcycles can benefit from the extra ZDDP for anti-wear and corrosion resistance.

AMSOIL Z-Rod 10w30
Z-Rod 10w30

The latest product to enter the market is the AMSOIL Z-Rod 20w50 (ZRF) and 10w30 (ZRT).  AMSOIL Z-ROD™ Synthetic Motor Oil is specially engineered for classic and high-performance vehicles. It features a high-zinc formulation to prevent wear on flat-tappet camshafts and other critical engine components, along with a proprietary blend of rust and corrosion inhibitors for added protection during long-term storage. Z-ROD Synthetic Motor Oil is designed to perform on the street and protect during storage. AMSOIL Z-ROD Synthetic Motor Oil is formulated with high levels of ZDDP to protect flat-tappet cams, lifters, rockers and other areas susceptible to wear. Its high-zinc, high-phosphorus formulation provides the extra wear protection these critical splash-lubricated components require.

AMSOIL Premium Protection 20w50 (ARO)
ARO 20w50

Next we have the AMSOIL Premium Protection Line. This is the “original” ultimate performance oil. Premium Protection comes in 10w40 (AMO) and 20w50 (ARO). Synthetic Premium Protection Motor Oil is formulated for use in both gasoline and diesel engines. Offers multi-functionality and excellent wear protection. Ideal for applications where the extra protection of a higher viscosity oil is desired. AMSOIL Premium Protection Oil exceeds the needs of large and small gasoline or diesel engines in cars, motorcycles, trucks, motor homes, maintenance equipment, heavy equipment, street rods and marine applications. It is ideal for high-mileage vehicles, vehicles with flat-tappet cams and high-stress vehicles subject to hot temperatures, heavy hauling, trailer pulling or off-road use. AMSOIL Premium Protection Oil resists oxidation, neutralizes acids, inhibits corrosion, reduces wear and protects against deposits. It provides the extra anti-wear protection required by engines with flat-tappet cams and high-tension valve springs. AMSOIL Synthetic 20W-50 Premium Protection Motor Oil offers flexibility and performance beyond conventional oil for convenience and trouble-free operation.

AMSOIL Serires 3000 5w30 (HDD)
HDD 5w30

AMSOIL Diesel Oils also contain higher amounts of ZDDP. The 15w40 and Series 3000 5w30

AMSOIL Series 3000 100% Synthetic 5W-30 Heavy Duty Diesel Oil (HDD) delivers extraordinary lubrication in both diesel and gasoline engines found in commercial, fleet and personal vehicles. By combining the industry’s premier synthetic technology with AMSOIL premium additives, AMSOIL Series 3000 exceeds the higher performance demands of modern engines. Even under high temperatures and pressures, AMSOIL Series 3000 Diesel Oil’s superior film strength and anti-wear additives help prevent metal-to-metal contact. AMSOIL Series 3000 reduces ring wear, cylinder bore polishing, oil consumption and valve train wear for improved engine life and lower maintenance costs.

AMSOIL Synthetic Heavy Duty Diesel & Marine Motor Oil 15w40(AME) is a premium diesel oil providing excellent performance in all types of diesel engines where highly effective control of wear and deposits is vital. Built with heavy-duty dispersant/detergent additives, its 12 TBN chemistry neutralizes acids and controls soot thickening from EGR and blow-by to protect against corrosion, cylinder bore polishing (wear) and varnish/sludge deposits. AMSOIL 15W-40 Diesel Oil resists heat and breakdown better than conventional petroleum oils for long lasting performance and protection.

AMSOIL Dominator Racing Oil
Dominator Racing Oil

Rounding out the high zinc oil line-up is AMSOIL’s racing specific oils. With AMSOIL, anyone can get the highest level of protection for racing (some companies develop specific oils for their race teams)

AMSOIL Dominator® Synthetic Racing Oil  provides superior performance and maximum protection in high-performance and racing applications. Formulated to withstand the elevated RPM, high temperatures and shock-loading common to racing applications, Dominator Synthetic Racing Oil delivers superior performance and maximum protection in extreme conditions. Its shear-stable formulation was engineered to provide maximum horsepower without sacrificing engine protection. Dominator Synthetic Racing Oil provides straight-grade protection in a multi-grade formulation. AMSOIL Dominator Synthetic Racing Oil features an additive package heavily fortified with zinc and phosphorus for superior long-term wear protection. Designed for maximum durability, it ensures critical engine components are protected for the duration of the race. Dominator Synthetic Racing Oil’s superior additive technology provides unmatched durability in extreme conditions.

AMSOIL Dominator Racing Oil is available in 3 viscosity grades.

Dominator® Synthetic 5W-20 Racing Oil (RD20)

Dominator® Synthetic 10W-30 Racing Oil (RD30)

Dominator® Synthetic 15W-50 Racing Oil (RD50)

AMSOIL Inc has created a Technical Service Bulletin about zinc and flat tappet camshaft wear. You can download the AMSOIL TSB Zinc and Flat Tappet Cams in PDF.

AMSOIL High Zinc Oil Recommendations Phosphorus Level (ppm) Zinc Level
Z-ROD™ 10W-30 Synthetic Motor Oil (ZRT)



Z-ROD™ 20W-50 Synthetic Motor Oil (ZRF)



Premium Protection 10W-40 Synthetic Motor Oil (AMO)



Premium Protection 20W-50 Synthetic Motor Oil (ARO)



Series 3000 5W-30Synthetic Heavy Duty Diesel Oil (HDD)



15W-40 Synthetic HeavyDuty Diesel and Marine Motor Oil (AME)



Dominator® 5W-20 Synthetic Racing Oil (RD20)



Dominator® 10W-30Synthetic Racing Oil (RD30)



Dominator® 15W-50Synthetic Racing Oil (RD50)



SAE 60 Super Heavy Weight Synthetic Racing Oil (AHR)




Q: Should you buy extra ZDDP additives and add to your motor oil?

A: The quick answer is No. Oil additives should not be used. The oil companies have gone to great lengths to develop an additive package that meets the vehicle’s requirements. Some of these additives are synergistic, that is the effect of two additives together is greater than the effect of each acting separately. If you add anything to the oil you may upset this balance and prevent the oil from performing to specification.

If you buy a properly formulated motor oil, there is no need to put any kind extra additives whatsoever this includes zinc based additives or any of the so call “slick” and prolong type additives. In some cases over time, the additives can cause more damage to your engine.

Q: Does more zinc (zddp) offer better protection?

A: No,  an overdose of ZDDP does not offer more protection. A properly designed oil will provide maximum protection throughout the recommended life of the oil drain.


Are you ready to order? AMSOIL’s factory direct pricing and order process is simple and easy to use.

To get the best pricing on AMSOIL products become a preferred customer and save 25-30%. Or better yet become an AMSOIL Dealer.

If you have questions or would like to order directly from Michael Sparks. Please visit my contact page. I will respond ASAP!  http://www.amsoil.lube-direct.com/contact/

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  1. says

    My ’64 Chevy still has the original 283 V8 under the hood. Thanks to CAFE, it’s gotten increasingly difficult to prevent engine wear. While I’ve used only synthetic oil in it for at least 20 years, it’s Amsoil Premium Protection & Z-Rod that give me peace of mind as far as the crankcase goes, For classic car owners, the fuel system is another major concern. Ethanol in today’s gasolines are wreaking havoc with mechanical fuel pumps, fuel line hoses and carburetors. If you’re fortunate enough to live in a state where you can find 100% gas, be sure to use it. It will cost a few pennies more, but you’ll get better performance & mileage, and you’ll be less likely to encounter a leaky fuel line hose during cruise night. Don’t forget to use a product like Amsoil Octane Boost as a lead substitute and octane booster. Your classic ride’s valves will love you for it.

    • says

      John your absolutely on target. AMSOIL products are designed to help classic automobiles and Hot Rods stay in top running condition. Don’t forget to check out the Advanced air filtration called Absolute Efficiency (Ea) Filtration.

  2. A. Dias says

    I noticed that Amsoil offers 2 European Car Formula 5W40 oils. One with mid-SAPS and the other full-SAPS. Do you know what are the Zn and P contents of those 2 oils?
    Also which version mid-SAPS or full-SAPS is recommended for a modern car?

    • says

      The AFL (Mid-SAPS) has about 800 ppm of ZDDP while the EFM (Full-SAPS) has about 1000 ppm of ZDDP in it.

      Remember that zinc is not the only indicator of protection and performance. The entire additive and base-stock formalization should be considered when choosing a motor oil. AMSOIL Synthetic European Formula products offer exceptional performance in European manufactured automobiles.


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