Top 7 Best Oil For Flat Tappet Cam Engine In 2024 [Recommended]

A flat tappet cam engine needs ZDDP or a diesel-grade oil with good zinc contents. Many cam lifters and lobes have died due to the use of modern non-zinc oils. The modern oil can’t provide that level of lubrication a flat tappet engine requires. 

On the other hand, zinc works as lube. It lubricates every camshaft follower & lobe and reduces metal-to-metal frictions. Indeed, zinc oil delivers unmatched engine protection by shielding wear & sludge. 

But the problem is- finding the right type of zinc oil that includes the proper amount of zinc and phosphorus is a pain in the neck. Therefore, multiple oil options make it challenging to pick the best oil for flat tappet cam engine. 

Fortunately, we found and tested the top 7 engine oils from the leading brand that ensures optimum engine protection. All of them include zinc to meet the requirement of your flat tappet cam engine. So, check them out by scrolling down. 

best oil for flat tappet cam engine

Comparison Chart of the Best Oil for Flat Tappet Cam Engine

Here is a quick recap of the oil we reviewed for your old car engine.

Product NameKey FeaturesBenefits
Valvoline VR1 Racing 20W-50 Motor Oil> High zinc and phosphorus formula
>Enhanced anti-foam system
> Compatible with a passenger vehicle
> Reduce friction and enhance power
> Lube every moving part optimally
> Provide extreme wear protection
Shell Rotella Synthetic Blend 15W-40 Diesel Motor Oil  > Advanced low-ash formulation
> Synthetic base oil components
> Advanced formulation
> Prevent the build-up to block your engine
> Enhance cold starting
> Deliver better engine cleanliness & protect your engine against piston deposits
Castrol GTX 15W-40 Diesel Motor Oil > Special viscosity improvers
> Anti-oxidant and detergent additives 
> Applicable for on and off-road heavy-duty 4-stroke trucks and cars
> Deliver optimum engine protection against piston deposits and oil thickening
> Provide unmatched engine performance under severe driving conditions
> Maintain cleanliness in hot running
AeroShell Oil W100 Plus> High viscosity index base oils
> Non-ash forming, polymeric additive
> Include Lycoming additive
> Protect engine components more effectively under the high shear stresses
> Eliminate the harmful combustion chamber deposits
> Give extra protection to engine parts against rust & corrosion
Lunati 15W-50 High Zinc Oil for Flat Tappet> ZDDP anti-wear additives
> Military spec storage protection
> Start-up protection additives
> Ensure your engine has unmatched anti-wear protection
> Rust & corrosion can’t damage your engine parts in winter storage
> Enhance overall engine performance
Amsoil Break-in Oil (SAE 30) > Zinc and Phosphorus anti-wear additive
> Film strength additive
> Viscosity grade oil
> Protect engine parts like lobes, lifters, and rockers from wear damage
> Boost up horsepower & torque
> Shield rod and main bearings from damage
Castrol 20W-50 Conventional Motor Oil > Formulated with superior base oils
> Patented additive technology
> Specially formulated to prevent sludge
> Extend engine life by protecting it from wear
> Prevent sludge build-up in severe driving conditions
> Provide better protection against volatility burn-off

How to Choose the Best Oil For Flat Tappet Cam Engine

A flat tappet cam engine requires a special type of zinc oil due to its unique design to protect it from wear, deposits, and sludge. The following considerations will help you to pick the right oil for your old car engine.

Check the Zinc & Phosphorus Level

First off, consider the amount of zinc & phosphorus the oil contains. Your flat tappet engine requires a high-level zinc oil to reduce the friction and protect it from wear. Pick the engine oil that includes 1000-1400 ppm zinc and the same level of phosphorus. 

Ability to Resist Rust & Corrosion

Whether the oil can resist rust & corrosion or not is the second criterion you need to consider. You don’t want to let rust and corrosion damage the internal parts of your engine when you don’t drive the car. 

For example, Lunati15W-50 Driven HR-1 High Zinc Hot Rod Oil includes a storage protection additive. It ensures to shield your car engine against & corrosion during winter storage. 

Include Extra Additive or Not

Zinc-based oil doesn’t need an extra additive to blend as it has the power to fight against wear, rust, and sludge. However, some oils like Lunati 15W-50 HR High Zinc Oil include Lunatic Additives to increase the oil strength. 


You can find a ton of engine oil options out there. But picking the right one is challenging. To avoid distraction, we recommend you to stay with the top oil brands like Castrol, Valvoline, AeroShell, Shell Rotella, and Amsoil. 


Price will not be a purchasing factor to get engine oil for your flat tappet engine. You should focus on quality over price. Always choose the engine oil that can protect your engine from wear, deposits, and sludge. 

7 Best Oil for Flat Tappet Cam Engine In 2023

Now, let’s check out the in-depth review of each product and discover what awe-inspiring features they include. 

Valvoline VR1 Racing SAE 20W-50 Motor Oil

Your high-performance racing car or flat-tappet car engine will never die again due to the lack of lubrication. Valvoline VR1 Racing Oil contains high-level zinc to provide race-level protection against friction. Its exclusive chemistry is designed to protect your flat tappet and cam engine, lubricating every moving part in the engine compartment. 

Valvoline VR1 Racing SAE 20W-50 Motor Oil

Key Features & Benefits

Discover why we ranked Valvoline VR1 20w50 at the top of our list. 

Ideal for Flat Tappet Cam Engine

Regular oil can’t provide that level of wear protection a flat tappet cam engine needs. Such a classic car with a flat tappet engine requires oil that contains a high level of zincs.  And Valvoline VR1 Racing Oil includes a high zinc and phosphorus formula for extreme wear protection. So, you don’t need to worry about the engine damage as this oil lube every moving part of your old car engine. 

Provides Superior Wear Protection

This engine oil from Valvoline is specially engineered to provide race-level protection in every classic & modern high-performance car. The oil contains zinc and phosphorus, which create an anti-wear layer by lubricating every engine part. As a result, no metal-to-metal friction will occur, which protects your car engine from wear damage. 

Boost up Engine Performance

Reducing metal friction means less pressure on your car engine. And the Valvoline VR1 20W-50 ensures a decrease in metal-to-metal contacts. It is specially formulated to maximize horsepower by reducing stress on the engine. 


  • Excellent oil for racing and older air-cooled engines
  • Reduce friction and increase power
  • Provide superior wear protection


  • Some users claim that all 3 jugs leaked out a little oil

In short

Valvoline VR1 Racing Oil is the best oil for flat tappet cam engine. It uses a high zinc and phosphorus formula to provide extreme wear protection by lubricating every moving part. 

Shell Rotella T 5 Synthetic Blend 15W-40 Motor Oil

Shell Rotella T5 15W-40 is our second pick for its excellent ability to protect the engine against wear, deposits, and oil breakdown. This engine oil blends synthetic base oil and advanced additive to deliver unsurpassed protection, even in low temperatures. 

Shell Rotella T 5 Synthetic Blend 15W-40 Motor Oil

Key Features & Benefits

Let’s figure out the breathtaking features of the synthetic diesel motor oil comes from Shell Rotella

Advanced low-ash formulation

The fuel efficiency of your vehicle will decrease due to the use of low-quality oil. The Shell Rotella Oil features an advanced low-ash formulation to handle deposits, poisoning of exhaust after-treatment devices. In other words, this synthetic oil boosts up fuel efficiency by maintaining vehicle emission compliance. 

Synthetic base oil

This synthetic base oil uses advanced formulation to deliver superior engine protection against deposit build-up, low temperature, and wear. It also improves cold starting and helps to reduce fuel consumption.  


  • Prolong the engine life by protecting the engine against wear
  • Reduce oil consumption
  • Improve overall engine performance


  • It would be great if the manufacturer improves the packaging

In short

Shell Rotella will be your go-to oil option if you want to protect your older engine from sludge, wear, and low temperatures.

Castrol GTX 15W-40 Motor Oil

Whether you use your car or truck for normal driving or heavy towing, Castrol GTX Diesel Engine Oil will keep your engine smooth. The heavy-duty diesel oil lubricates every moving component of your car engine and reduces friction. In return, it gives your engine long and healthy life. 

Castrol GTX 15W-40 Motor Oil

Key Features

Here are some unique features Castrol GTX Diesel Motor Oil includes.

Offer Reliable Engine Protection

The Castrol Diesel Oil is specially formulated to shield your engine against piston deposits, oil thickening, and valve train wear. Therefore, it gives ultimate engine protection against viscosity loss. All of these contribute to increasing the lifespan of your old vehicle engine. 

Provide Exceptional Engine Performance

Metal-to-metal friction will increase when you drive your car under severe conditions like extreme cold or high temperatures. And this engine oil from Castrol keeps your engine parts well-lubed, and the engine runs smoothly in hard-driving situations like towing & hauling. 

Multi-purpose Oil

It’s versatile engine oil, and you use it in a wide range of vehicles including, commercial vehicles, trucks, and passenger cars. The engine oil features anti-wear, anti-oxidants, and detergent additives to handle rough conditions without damaging your engine. 


  • Ideal for multiple vehicles like car, truck, and commercial cars.
  • Protect your engine from wear & deposits
  • Improve overall engine performance by reducing stress


  • Some users claim that the oil comes in a Walmart box and tape as they ordered on Walmart.

In short

If you want to get a multipurpose oil that you can use both in a car and truck, go for Castrol 03849-3PK GTX Diesel 15W-40 Motor Oil.  

AeroShell Oil W100 Plus

Do you want to get engine oil that offers aircraft-grade engine protection and performance? Then, AeroShell Oil W100 Plus is what you look for. It combines both AeroShell ashless dispersant technology and advanced antiwear additives to ensure optimum engine protection. 

AeroShell Oil W100 Plus

Key Features & Benefits

Check out how AeroShell Oil ensures the ultimate protection of your classic car engine from high temperature, wear, and sludge. 

Offer Ultimate Rust & Corrosion Protection

This aero-craft grade oil provides ultimate protection against rust & corrosion. The oil keeps every part of your engine lubricated whether you operate your car regularly or not. In return, corrosion can’t make a home in your engine compartment to ensure longevity. 

Enhance Anti-wear Characteristic

Most flat tappet engines need a higher level of lubrication at engine start-up. And AeroShell Oil well-lubed your engine parts and improves the anti-wear characteristics with no extra supplemental additives. It already includes Lycoming additives in correct proportions to meet the needs of your flat tappet cam engine. 

High Viscosity Index Base Oils

The non-ash forming oil maintains its viscosity and provides ultimate engine protection under high shear stresses. Therefore, this aircraft-grade oil helps to eliminate the harmful deposits that form in the engine compartments at normal operation. 


  • Remove harmful sludge and deposits from the engine compartment
  • Offer greater rust & corrosion protection
  • Protect your engine against wear & high temperatures


  • A bit expensive

In short

It will be your go-to engine oil to protect your old car from sludge, wear, and high temperatures. Plus, it includes Lycoming additives. So, you don’t need to spend extra bucks to get oil additives. 

Lunati15W-50 High Zinc Oil for Flat Tappet Camshaft

HR Conventional 15W-50 is an advanced petroleum motor oil. It is specially formulated to provide unsurpassed protection and performance in muscle cars and flat tappet camshaft. The race-proven technology includes the right amount of zinc to protect your engine against wear. 

Lunati15W-50 High Zinc Oil for Flat Tappet Camshaft

Key Features & Benefits

Let’s see what breathtaking features the HR1 High Zinc Oil includes to let your flat tappet engine run smoothly.

Design for High-performance & Flat Tappet Cam

Modern motor oil will not provide that level of lubrication a variety of rods, muscle cars, and classic cars need. Such types of the engine require a strong additive with zinc. And the Lunati DRVO2107 HR Oil is what your high-performance and flat tappet camshaft needs. It is formulated with the proper amount of ‘fast burn’ zinc to provide unmatched wear protection. 

ZDDP Anti Wear Additive

You don’t need to spend extra bucks to get zinc additive to add with the oil. The Lunati HR Oil includes ZDDP additives to ensure your flat tappet camshaft has critical anti-wear protection. 

Military spec storage protection

Unlike other oils, the HR1 High-zinc Rod Oil from Lunati features the US military-spec storage protection ZDDP additive. As a result, it shields your car engine against rust & corrosion during winter storage. 


  • Resist rust and corrosion optimally
  • Offer excellent seal compatibility
  • Provide ultimate wear & tear protection


  • Too expensive

In short

If you are easy with the budget and want to get the best oil for muscle cars and flat tappet camshaft, Lunati DRV02107 HR1 Oil will be your go-to option. 

Amsoil Break-in Oil (SAE 30)

Amsoil Break-in Oil is one of the best oils for flat tappet cam engines. It includes zinc and phosphorus formulated to give the optimum protection against wear, sludge, and film deposits. 

Amsoil Break-in Oil (SAE 30)

Key Features & Benefits

Like other zinc oils, the Amsoil Break-in Oil includes the following features to ensure your classic car engine has the optimum wear-protection capability.

Unmatched Wear Protection

The SAE 30 viscosity grade oil contains zinc and phosphorus additives to ensure the ultimate protection of your engine components. It lubricates every moving part of your old engine and protects cam lobes, lifters, and rockers during the critical break-in periods when the wear rates are highest. 

Film Strength ZDDP Additive

This zinc oil comes with a film strength additive to reduce the friction between metals. As a result, the motor oil with zinc protects the rod and main bearings from damage. 

Increase Overall Engine Performance

Increasing overall engine performance by protecting the engine from wear is the key behind manufacturing oil. And this zinc oil from Amsoil lubes every part of your engine. Therefore, it offers superior wear protection which reduces the stress of the engine. In return, your car engine runs smoothly and boosts up horsepower & torque for gaining maximum engine performance. 


  • Increased zinc and phosphorus offer unmatched wear protection
  • Prevent metal-to-metal friction
  • Enhance compression and power


  • Price is too high

In short

It will be the best oil if you want to protect your flat tappet engine from wear & sludge and improve the horsepower & torque to boost up engine performance. 

Castrol GTX 20W-50 Conventional Motor Oil

Castrol GTX 20W-50 is another best oil for a flat tappet cam engine. It is specially used in older cars or warm climates. This oil is formulated to prolong the longevity of your car engine by preventing the sludge build-up, even when you drive in extremely high temperatures. 

Castrol GTX 20W-50 Conventional Motor Oil 

Key Features & Benefits

Figure out what incredible features Castrol GTX Conventional Motor Oil includes. 

Stop Sludge Build-up

The motor oil from Castrol is specially engineered to remove existing sludge. At the same time, it also prevents new sludge formation. As a result, sludge can’t bring any damage to your engine, which extends your vehicle engine life. 

Phosphorus Replacement Technology

You don’t need to worry about the protection of your vehicle if you drive over 75000 miles. The oil features Phosphorus Replacement Technology to reduce the level of phosphorus with the replacement of proprietary additives. In other words, it protects your emission system by shielding robust wear & sludge. 


  • Reduce oil deposits
  • Prevent sludge formation
  • Protect your engine against wear


  • Some users claim that they get oil soaked box

In short

It will be your best pick if you want to protect your old engine from sludge build-up and high temperatures.

Watch and know why flat tappet cams engines need high zinc oil:


Is Rotella good for flat tappet cam?

Yes, Rotella is a good oil that contains a high level of zincs that your flat tappet cam engine needs. 

How do I know if my tappet cam is flat?

If you have trouble starting the engine and it makes a popping noise, understand it may be you own a flat tappet engine. 

Can I put roller lifters on a flat tappet cam?

Yes, you can put roller lifters on your flat tappet camshaft. 

What causes a cam lobe to go flat?

Lack of zinc in modern oil can cause a cam lobe to go flat. 

Should I use conventional oil or synthetic oil on my flat tappet cam?

You should use conventional oil on your flat tappet cam engine because the old engine needs high zinc oil to reduce friction. On the other hand, synthetic oil is slippery and lubricated which will cause problems with your old engine. So, always avoid synthetic motor oil in case of a flat tappet. But, you can use it in your roller cam.

Can I use race oil on my flat tappet cam?

Yes, you can use race oil as racing oil caries zinc with a high ZDDP level.

Can I run roller lifter or hydraulic lifter on a flat tappet cam?

Yes, you can run a run hydraulic flat tappet lifter on your solid flat tappet camshaft.


The camshaft design of a flat tappet engine makes it crucial to pour high zinc oil into the car. Zinc oil effects on flat-tappet are high as the zinc creates a layer to reduce metal friction by lubing every internal part of an engine. 

Every oil we recommended above contains zinc and phosphorus to fight against wear, deposits, and sludge. Each of them delivers unmatched lubrication to protect your flat tappet engine against friction & wear. 

So, you can choose any oil from the list of the best oil for your flat tappet cam engines. 

About John M

John contributed as a technical head at an automobile company just 2 years after his post-graduation in Automobile Engineering. He loves to lead a free life, so he left his job & started blogging. Now, he does research on every automotive problem, part & product and seeks a better solution & best products & shares his findings with his readers to help them as well as to minimize their struggle.

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