The engine is the lifeline of your vehicle and it demands adequate maintenance for its proper and longer functioning.

Lubrication of an older engine with high mileage oil is a great idea to keep it functional in the long run. 

However, the importance of oil additives in engine oil is undeniable, without question. Engine oils alone cannot facilitate the proper operation of a high-mileage vehicle.

Older engines often make noises and are more prone to wear and tear due to friction. They require oil with durable viscosity.

The best oil additives for older engines also encourage cleaning and lower engine noise in addition to improving viscosity.

By the end of this article you’ll find the best oil additives for your old engine, their main types, and a buying guide, we have got you covered in all ways. 

Without further due, let’s check out the top-rated options for the best oil additives for older engines.

Which are the best oil additives for the older engine?

  1. Archoil AR9100
  2. LUCAS LUC10130
  3. Bestline Engine Treatment Oil
  4. Marvel Mystery Oil 50735
  5. Liqui Moly 2037 Engine Flush
  6. XADO Engine Oil Additive
  7. LUCAS Oil 10063 Engine Break-in
  8. Castrol 03128C Edge
  9. XADO Engine Oil System Cleaner
  10. Slick 50 Engine Treatment

1. Archoil AR9100

Archoil is the real deal when it comes to dealing with stalling and idle issues of an old engine during extreme weather conditions.

This oil is designed to protect each component of the engine during cold starts. The components of this oil additive possess anti-wear and anti-corrosive properties that extend the life of an old engine.

This oil additive is the best for older engines as it creates a lubricating film. It protects and regulates the smooth operation of each part of the engine.  

The strong lubricating power reduces friction between the engine parts so the engine produces less heat. Less heat means the engine works better and creates no noise.

The cleaning agents of this oil additive eliminate sludge and varnish residues and keeps the engine clean.

You’ll definitely swear by this oil once you experience its efficacy. It will help you get rid of all the stiction issues and treat bad injectors

When used in appropriate composition with the engine oil, this oil additive will reduce all those annoying engine noises and vibrations. 

It eliminates the friction that halts the smooth working of the engine. Using this oil additive will also extend the oil drain intervals.

Also, it prevents engine oil from turning acidic during these intervals. Overall, this is a good choice for all high-mileage engines since it eliminates noise, and reduces friction as well as oil deposits.

Eliminates hard/cold start issues
Works well with all diesel and gasoline engines
Compatible with conventional and synthetic oils
Most power stroke difficulties can be resolved, but not all
Not 100% efficient in extreme weather conditions

2. LUCAS LUC10130

If you want to keep your old engine alive for a longer time, this oil additive from Lucas is the answer.

Lucas is an option trusted by vehicle owners worldwide. This oil additive noticeably increases the efficiency of the motor oils and keeps the engine working smoother than ever

LUC10130 is a synthetic oil stabilizer that definitely renders better fuel mileage. This oil has been engineered primarily to reduce friction between the components of the engine.

You’ll be surprised by the increased performance of your engine with this oil additive.

It will virtually eliminate wear and corrosion of the engine parts. Forget about those random ticking noises generated by the bummed carburetor of the engine with this oil additive.

This is without a doubt among the best oil additives for older engines because it fixes all the problems with older engines, such as rough idle and dry starts.

It will extend the oil and engine life. Additionally, it avoids an overheated engine by maintaining a consistent oil temperature.

This oil additive contains anti-knocking agents. It will also help you get rid of smoking and leaking motor oil.  

The engine oil remains tacky and sticks to every inch of the engine as its viscosity remains stable with this oil additive. There’s honestly no going back once you try out this oil additive from Lucas!

Compatible with all grades of oil
Renders a smoother and quieter running engine
Eliminates friction
Most efficient with Ford power stroke engines only

3. Bestline Engine Treatment Oil

Increase the life expectancy of the old engine of your vehicle with this oil additive which is one of a kind.

It comes with diamond nano-lube technology to provide boundary layer protection to your high-mileage engines.  

This engine treatment oil has been manufactured in the USA and it is designed to provide powerful performance to every vehicle.

The great thing about this oil additive is that it doesn’t use any old-school ingredients like Teflon or PTFE. It comes only with the latest high-quality constituents.

This oil will improve the fuel efficiency of your vehicle and keep it functioning at its best in the long run. This oil additive will cut down internal friction and reduce the wear of loaded mechanical surfaces.

The anti-corrosive agents will protect your old engine from corrosion. It will clean and treat the internal components of the engine rendering greater efficiency.  

Bestline is a fully synthetic oil additive that offers great protection against engine wear. It also lessens the overheating of the engine which makes it suitable for regions with a hot climates as well

The increase in engine life is guaranteed by this product. The best part about this oil additive is that it reduces the instances of pre-ignition or smoking and it will help you get rid of those ticking noises.

The drain intervals are going to be longer than usual thankfully. It works with every kind of engine oil. Use one bottle with each oil change for the best results.

Works with foreign and domestic vehicles
Compatible with both gas and diesel
Improves fuel economy
Not compatible with Toyota oils
A bit expensive

4. Liqui Moly 2037 Engine Flush

One of the best oil additives for older engines that can be utilized to remove the excessive buildup of sludge or residues in an old engine’s components has to be this Engine flush from Liqui Moly.

Liqui Moly is without a doubt, the most popular brand of motor oil from Germany. It has been manufactured specifically to restore the performance of older engines by cleaning up deposits and residues from all 4-stroke gasoline and diesel engines.

Flush out all the sludge with this oil additive and get rid of annoying engine noises. Unlike most detergent additives that affect the lubrication of the motor oil, this one from Liqui Moly recovers the lubricating oil properties.

Also, it is not problematic for seals in the engines so you don’t have to worry about the detergent damaging any part of the engine.

It will also prevent the engine parts from corrosion and improve combustion. This oil additive is a sort of detox for the engine of your old vehicle.

It will remove all the gunk and deposits rendering a smooth operation of the engine. Unlike other oil additives, this one needs to be added before the engine oil changes.

Empty the contents of the bottle in a warm engine. Let it stay idle for 10 minutes and drain the oil. Your engine will be cleaner than ever and you’ll notice a significant difference in the performance of your vehicle.

Compatible with all commercial engine oils
Flushes out all the sludge/gunk
Restores engine performance
Does not give results right away

5. XADO Engine Oil Additive

Boost the performance of the engine of your vehicle with this oil additive and avoid expensive repairs.

This engine oil from Xado is created to provide extra light sliding between the parts of your old engine. The smooth function of the piston and valves will promote a very improved performance of your vehicle. 

It is one of the best oil additives for older engines as it helps in restoring the worn-out surfaces of the engine. Moreover, apart from the restoration, it also creates a protective film against any future wear.

A ceramic metal coating is formed on the engine parts to neutralize the worn-out surfaces. This oil additive is also great for eliminating engine noises and vibrations.

The noises are usually commonplace to occur in older engines. It reduces friction and gives the boost of power your high-mileage engine needs.  

Also, it greatly increases the power and acceleration of the engine. It is compatible with all types of motor oils whether synthetic or mineral.

For a complete revitalization cycle of the engine, a 600-900 mile drive of your vehicle is mandatory. This oil additive is suitable for all gasoline-powered, natural gas, and diesel engines.

Restores worn-out surfaces
Prevents future wear by forming a protective coat
Compatible with all types of engines and oils
Fuel mileage remains the same

6. LUCAS Oil 10063 Engine Break-in

Another great product from Lucas is for classic car and race engine owners. It is one of the best oil additives for older engines of your vehicles. It is strictly not recommended for passenger cars.

However, this is the greatest oil additive for all racing engines. It is highly efficient in protecting camshaft lifters and valve trains during the critical time of engine break-in.

Most modern motor oils lack zinc which is very crucial for protection against wear and corrosion. So what is most likable about this oil additive is that it contains the good old zinc that possesses anti-wear properties.

It will prevent all the engine parts from corrosion and wear. It is an amazing option for racing engines as it is a blend of extreme-pressure additives that are required in racing applications.

It is great for all engines with flat tappets. This oil additive is a high-quality product with great value for money.

It makes the engine run time lesser which makes it good for racing vehicles. Also, it is rich in zinc so it helps to increase the zinc concentration of your regular motor oil which in turn prevents wear of engine surfaces. 

All in all, Lucas products never fail to meet the expectations of its customers. This product absolutely does what it claims.

Compatible with flat tappets camshafts
Prevents premature wear
Renders a lesser engine run time
Not recommended for passenger cars
Designed for classic cars and race engines only

7. XADO Engine Oil System Cleaner

It is great life support for all the old vehicles. This is another great product for cleaning your engine oil system.

It is probably the best oil additive for older engines with a detergent powder. If you’re someone who doesn’t religiously follow the clean-up regimes of their vehicle then it is definitely the right option for you.

This oil additive will thoroughly clean even the dirtiest of engines. Xado engine oil cleaner will remove all the contamination and engine sludge.

It will also help eliminate carbon deposits and restore the mobility of the piston rings that are stuck due to excessive residues/gunk.

This oil additive also contains anti-wear agents that will prevent engine parts from any damage. It is a purely synthetic product and will increase the oil viscosity, helping it to stay thick for a longer time. And hence, protecting the engine surfaces from friction.   

Aside from all the cleaning functions, it also prevents leakage as this oil seals all the minor cracks that result from corrosion. Both diesel and gasoline engines can use it. 

Also, it prevents contamination of fresh engine oil by removing the residuals of the previous oil.

Compatible with all engine types, including turbocharged engines
Restores mobility of stuck engine parts
Seals minor damages and cracks
Doesn’t work well in cold weather

8. Castrol 03128C Edge

The effectiveness of this oil additive is like no other. It is a synthetic oil additive with amazing results.

You’ll be surprised to see how your engine runs smoothly and quietly with the use of this oil additive in your engine.

It stands in our list of best oil additives for older engines for this very reason. Castrol 03128C has been designed especially for engines over 75k miles.

So know that it’s going to work great for your old engines undoubtedly. This synthetic motor oil has been proven to perform well even under high temperatures.

It will help your high-mileage engine keep its cool. Also, it enhances motor oil strength. Castrol adheres to each engine and allows a very effortless functioning of the engine.

Not only does it improve performance but also provides protection to the engine. It eliminates friction between the surfaces.  

Unless you like your engine talking, you will be delighted about how this oil makes the engine quieter immediately.

It has been tested for reduced leakage and less oil burn-off. The oil protects catalytic converters and eliminates power-robbing deposits. It will improve fuel economy as well as engine life.

Specifically designed for high-mileage engines
Sticks to engine valves and reduces friction
Performs well even under high temperatures
Gets dirty relatively quicker

9. Slick 50 Engine Treatment

Lastly, this engine oil treatment from slick is not less than any other. It is also one of the best oil additives for older engines to restore their lost performance.

So it is a great option for every high-mileage vehicle. Your engine will now run cooler and start faster. This oil additive provides protection against power-robbing friction.

It has proven to give great efficacy in eliminating friction. Slick 50 forms a protective layer of lubricant around the engine surface to minimize the damage of friction.

Also, it works effectively when it comes to reducing heat up in the engine. This engine treatment oil also has wonderful cleaning power.

It cleans and helps to get rid of the sludge build-up. In addition to that, it also prevents any such future build-up in the engine parts. 

Thus it revitalizes the seals that have been compromised due to corrosion and helps to reduce oil leakage. 

Using this oil, you’ll notice maximized fuel economy and a boost of power and performance in your engine. It also prevents any kind of wear and promotes a very smooth and quiet operation of the vehicle.

Compatible with all grades of oil; multigrade/monograde
Revitalizes seals
Restores lost engine performance
Offers only 15oz of product

10. Marvel Mystery Oil 50735

Marvel has proved its effectiveness and worth time and again. When we say it is one of the best oil additives for older engines, we mean it.

It is manufactured to provide lasting lubrication to each part of the engine. Improves performance and makes your old engine work like a fairly new one

The marvel mystery oil is the ultimate fuel and motor treatment. It will help your engine retain its strength and efficiency.

Older engines have had their fair share of intense operation. It makes them more prone to issues like stalling, cold starts, or wear due to friction.

They need a classic product like this mystery oil that stabilizes the fuel for easy startups. The majority of high-mileage vehicles require oil additives to stop rust and corrosion in their engines.

Additionally, because it decreases friction between the engine parts, this amazing mystery oil is effective at preventing corrosion and wear.

This oil additive not only will keep the engine clean from sludge but also clean and prevent carbon deposits. It definitely treats a wide range of engine ailments, however, it is best known for reducing friction. 

Reduced friction will obviously lead to a smoother function of the vehicle without any problematic noises. Additionally, it nearly supports every engine type, extending its lifespan and improving performance.

Compatible with all engines, including GDI and Hybrids
Prevents sludge and carbon build-up
Extends engine life and peak performance
Slightly high in cost

Best Oil Additive for Older Engines: Buying Guide

You need to be aware of a few important characteristics that affect an oil additive’s effectiveness before you purchase any for your car.

First, let’s get to know some of the main types and best manufacturers of best oil additives for older engines. Then we will move on to the buying guide.

Types of Oil Additives

Oil additives come in a wide variety and are sold on the market. There are some that are designed for one purpose and, there are others that will prove to be an elixir of life for your overworked engines.

Some of them may be rich in antioxidants while others may regulate the viscosity or eliminate friction and so on.

Viscosity Stabilizers

Engine oil loses its viscosity over a period of time. The performance of the car is halted by the motor oil’s runny or water-like consistency.

Therefore, oil additives that help in maintaining the viscosity of the oil for a longer period of time are highly recommended.  

Thicker oils adhere to the engine surface a lot better and form a more strengthened lubricating layer.

Oil additives that render a stable viscosity as the Lucas LUC10130 mentioned in number 2 provide greater lubrication power and enhanced performance of the vehicle.

Friction Eliminators

Friction in high mileage engines causes a lot of wear and damage to the part of the engine. Also, heat is produced as a result of friction which then causes the engine to heat up.  

For your car to continue operating as intended, an oil additive that lubricates the engine and reduces or eliminates friction is essential.

XADO Engine oil additive eliminates friction to a great extent and renders an extra light sliding between the engine parts. Moreover, this oil also restores worn-out surfaces due to friction.

Detergents / Cleaners

If you’re getting your hands on a used vehicle and you are unaware of its cleaning regimen, you need to get the oil additives that offer detergent powder. 

All the residues and deposits are removed with the aid of these cleaners. Flush out all the sludge and contaminants from the previous oils and leave your engine anew.

XADO Engine oil cleaner and Liqui Moly 2037 are two such options in our list that work as a detox for your old engines. Both of them are the best oil additives for older engines that flush out all the excess gunk buildup in your vehicle.

Best Oil Additive Brands

There are many options that result in respectable oil additives.

However, there are a few of them that have made their mark worldwide by proving their efficiency time and again. We have mentioned a few of them.


The foundation of this brand was laid with the aim to produce the best and most effective line of oil products and additives. And these producers have met their expectations.

By creating the best oil additive in the entire world, they have demonstrated a strong commitment to their goal.

Customers rely on Lucas for their engine ailments and it is also one of the fastest-growing additive lines in the automotive industry.


It is also one of the leading suppliers of oil additives all around the world. The oil additives from Archoil come with the latest technology.

It faces all the challenges of modern engines without breaking a sweat.  

Their oil additives provide superior protection and lubrication to the engines. It helps in the restoration of the lost power of older engines.

They produce oil additives that are compatible with a vast variety of engines and motor oils. All in all, oil additives from Archoil are a versatile option.


Liqui Moly is a globally renowned brand of oil additive and lubricant manufacturers. This manufacturing company is based in Germany, however, it has consumers the world over.  

They are known to produce environmentally friendly products. Their oil additives are problem solvers everywhere.

Apart from increasing the efficiency of the engine, oil additives from Liqui Moly also increase the life of high-mileage engines. They help in boosting driving enjoyment while effectively cutting costs in the long run.

What Should Be Considered While Buying The Best Oil Additives For Older Engines?

If you are looking to treat a specific issue then, you may choose a function-specific oil additive.

Else it is always a great idea to purchase an all-rounder. Here are some of the things that you should not miss while purchasing an oil additive.

Temperature Resistance

The effectiveness of the oil additive depends a lot on the temperature usually.

If you live in a place that experiences extreme weather conditions, you should look for additives that stand the challenges of the weather.  

Most oil additives turn obsolete at extreme hot or cold conditions. Therefore, consider buying an oil additive that is adaptable to temperature.

Castrol 03128C at number 8 is a great option if you want something that does not lose its efficiency at high temperatures.


Some of the oil additives are not compatible with every type of engine and motor oil. Look for something that offers diverse options with limited restrictions.

You should buy an oil additive that is compatible with your vehicle. However, it is best to buy a broad-spectrum oil additive that works fine with both diesel and gasoline engines.

They should be compatible with all grades of motor oils synthetic, mineral, multi-grade, or monograde.  

The greater the versatility, the better. Almost every option in our list offers compatibility with a variety of engines. There are not many or rather any limitations to most of them.

Range of Use

Oil additives come with many purposes. Some of them are conditioners, while others are made to treat seal swells. 

They may be used for anti-oxidation or cleaning purposes. Also, to regulate the viscosity of the motor oil, or eliminate friction between the engine parts.

Always buy an oil additive that offers a wide range of use. Most of them are in one option while some are designed specifically for cleaning or engine break-in. 

However, the best oil additives for older engines are the ones that can treat engine noises, clean out sludge, and improve viscosity, all at once.

Older engines suffer from a variety of ailments so you will definitely need a versatile oil additive for their treatment.

Chemical Composition

Oil additives are composed of a variety of chemicals. There are some that surpass others in their importance.  

Zinc and Phosphorus are two such components and their presence in an oil additive makes it a lot more effective.

Zinc contains amazing anti-wear properties. It means that an oil additive containing zinc is very efficient in eliminating the wear on engine surfaces.  

Phosphorus helps in increasing the life of the engine as it helps in reducing friction to a huge extent. An oil additive with phosphorus will definitely cut down internal friction better than one without it.


Archoil AR9100 is an all-rounder on our list. It has been manufactured specifically for the treatment of older engines.

A visible difference will be noticed with the use of this oil additive. It eliminates excessive heat up and allows the engine to remain cooler for a long time.  

We consider it an all-rounder since it works well under high temperatures as well. It maintains the viscosity of the motor oil and strongly adheres to each part of the engine.

This oil reduces friction and makes the engine quieter and smoother than before. It eliminates high oil burn-off and increases fuel economy. Overall, it boosts the power of older engines.

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