Best Oil Additive for Older Engines

The oil additive industry is ever-growing, with products tailored to keep new engines new, and other products designed to improve engine performance in older vehicles, it can be confusing to tell the difference.

Older engines require extra help in order to operate like they did when they were new, and there are a variety of products out there than can help you achieve this. With special features such as reduced engine noise, increased MPG and minimised emissions, the benefits of oil additives are endless, however they all ultimately work to ensure your engine runs smoother. 

To aid in your search for the best oil additive for older engines, we’ve put together this list of the 5 best oil additives on the market, complete with all the important information you need to know about each one.

We have even included a handy buying guide, with its own FAQ section to help you understand how we’ve ranked these products and the key things to look at when making a purchase of your own.

In a hurry?

If you’re in a rush to get your hands on an oil additive why not try out our first choice for older engines?

We think the Lucas 10001 Heavy Duty Oil Stabiliser is the best oil additive on the market, this 32oz bottle goes a long way and has so many benefits on top of ensuring a smoother engine. 

Here’s a full list of all the key features that led us to this decision: 

  • 100% Petroleum product which increases the lubricity of motor oil and reduces oil consumption and operating temperatures.
  • Powerful formula means you don’t need to use much and a single 32oz bottle goes a long way.
  • Reduces engine noise, and controls heat and wear in both gas and diesel engines.
  • Highly effective with older engines and also with new engines for a quiet and smoother run.


Our favourite oil additive for an older engine on the market is the Lucas 10001 heavy duty oil stabaliser.

Available in 32oz bottles, helps prolong engine life in a variety of ways, including reducing oil consumption and increasing oil life by 50%. Lucas 10001 raises oil pressure, eliminates dry starts and is known to increase both power and miles per gallon in your vehicle.

This product is also known to reduce engine noise, as well as control heat and wear in manual transmission vehicles.

This 100% petroleum product gives the engine a higher degree of lubricity not only reducing oil consumption as previously mentioned, but also providing a greater control over operating temperatures. 

Lucas oil advertises this product as keeping old engines alive and new engines new, and with no notable drawbacks, Lucas 10001 really is the best oil additive on the market for older engines. 


  • Reduces engine noise
  • Makes the engine run smoother
  • Powerful formula means you don’t need to use much so one bottle goes a long way
  • 50% longer oil life
  • Suitable for gas and diesel engines
  • Controls heat and wear
  • Reduces oil consumption
  • More effective in older engines


  • No notable drawbacks 


One other great oil additive on the market is the Bestline Premium Synthetic Engine Treatment.

This product does everything you would want from an oil additive, including increasing the power and gas mileage and reducing friction within the engine with its diamond nano-lubricant which creates a protective layer on the metal within the engine. 

Bestline Premium is a 100% pure synthetic engine treatment, which allows it to be used in both gas and diesel engines in cars, trucks,, and motorcycles.

As well as reducing friction within the engine, Bestline also cleans and treats the internal components within your cars engine and fortifies it against oxidation and thermal breakdown. 

An all-round great oil additive, Bestline Premium comes in 12oz bottles which ensure smoother starts and maximum engine protection for your car, no matter the age. 


  • Increases overall mileage per tank
  • Reduces engine “chatter” and startup noise
  • Better for the environment as it minimizes harmful emissions
  • 100% pure synthetic
  • Compatible with all motor oils
  • Suitable for use with older engines
  • Reduces heat, wear,, and friction within the engine


  • Only available in 12oz bottles


Another excellent oil additive to consider is Liqui Moly 20002 CeraTec. Available in 300ml bottles, CeraTec is mixable with all commercially available oils and compatible with both gas and diesel engines.

Unlike many other oil additives on the market, Liqui Moly 20002 is resistant to both hot and cold temperatures making it an excellent additive to buy if the environment you drive in is prone to extreme weather conditions.

This product is compatible with all commonly used filter systems, and works to remove deposits from the filter system, therefore reducing engine friction. Liqui Moly 20002 works quickly with noticeable results such as a smoother engine, reduced engine noise and reduced friction.

With the only negative of this product being its strong smell, it is easy to see that Liqui Moly Ceratec is one of the best oil additives on the market. 


  • Reduces fuel consumption
  • Reduces friction in the engine
  • Removes deposits and build ups from the filter system
  • Reduces engine noise
  • Makes the engine run smoother
  • Works quickly


  • Strong smell


The SF-16 Motor Treatment product by SeaFoam is another great oil additive for an older engine.

Available in 16oz bottles, this 100% pure petroleum product works in a variety of ways to enhance engine performance in your vehicle. Unlike some other oil additives, SeaFoam SF-16 works not only on the engine but gives a more thorough clean, working on the injectors, carb jets and passageways in the engine too.

This product cleans and lubricates the engines intake valves, pistons and cylinders ensuring better engine performance and prolonging engine life. This motor treatment dissolves oil deposits in the crankcase reducing the chance of corrosion and improving the vehicles acceleration, while also cleaning the timing chain to ensure a quieter engine noise.

However, this product does sometimes struggle to perform to its full potential in extremely low temperatures and so this should be taken into account when making a purchase. 


  • Very effective
  • Improves acceleration and engine performance
  • Works in both low and high mileage vehicles
  • Extends the lifespan of all vehicle parts
  • Reduces engine noise
  • Compatible with gas and diesel engines


  • Struggles to perform in low temperatures


The final oil additive for old engines on this list is Marvel Mystery Oil, how this additive works is a mystery, but the results are clear.

Marvel mystery oil works to improve compression, power, and miles per gallon in your vehicle, while also lubricating the upper cylinder so that your engine runs smoother while idle.

On top of this, the oil additive cleans and lubricates the fuel injectors and carburetors while also preventing valve sticking and clatter for a smoother and quieter engine.

Ultimately Marvel Mystery Oil works to retain the cleanliness of your engine for better operation, and is compatible with all oil types and works incredibly well with older engines.

However, it does not eliminate high heat levels in some older engines which should be considered when making a purchase. 


  • Lubricates the cars engine and some engine parts which other oils do not cover
  • Improves all-round vehicle performance
  • Helps the engine oil run smoothly in extreme weather conditions
  • Slows down the process of rusting even in cold temperatures
  • Regular use reduces engine failure and prevents the engine from overheating
  • Removes sludge from the engine


  • Does not eliminate high heat levels in some older engines

Best Oil Additive for Older Engines Buying Guide

As cars age, it is common for engine performance to deteriorate as they can no longer operate as smoothly as they once would, how do you fix it? That’s where oil additives come in.

The best oil additives work with engine oil to improve performance and allow vehicles to run like new. So how do you know which oil additive is the best? 

With so many oil additives on the market, all offering different benefits, we understand that it can be difficult to decide which one is the best for you. To help we’ve put together this guide full of all the important things you should consider when buying an oil additive for an older engine. 


One very important thing to consider when buying an oil additive is whether or not it is compatible with your vehicles engine and fuel type. Although an increasing number of oil additives work with both diesel and gas engines, it is definitely something that you should watch out for as many products are still only compatible with one type of engine.

To be safe it is always best to check your vehicle’s manual to know what type of oil treatment you should use and which to avoid, especially as some manufacturers will advertise their product as compatible with all engine types when this is not actually the case.


A common issue with oil additives is that a lot of products struggle in extreme temperature, more often being affected by cold weather. It is important when buying an oil additive to consider the area where you live, the environment you drive in and the season you are looking to buy the product in as all of these will have an impact on what is the best oil additive for you.

Ultimately the best product would probably be one that can operate efficiently in both cold and hot climates, and there are a lot of oil additives that do this on the market. 

EPA Certification

In recent years people have become more aware of the impact our actions have on the environment, and as such EPA certification has become more important in oil additives.

EPA certified products have a variety of benefits including reducing harmful emissions from your engine, which not only improve fuel economy but also help the environment simultaneously.

An EPA Certificate basically means that that product does not contain harmful substances and that it is a better choice for the environment, so this is definitely something to consider when making a purchase. 

Features to Consider

As you look at different oil additives, one thing you will definitely notice is all the different features these products are advertised as having. Common features to consider include: reducing friction, increasing MPG, preventing rust and reducing engine noise, however all oil additives work to increase engine performance.

Different features may seem more important to you, for example if your engine is noisy you might prefer an oil additive which reduces noise, or if you have a greater interest in speed, an additive that increases MPG might be better.

Like any product, every oil additive will have its own unique features so it is important to consider exactly what you want out of the product before making a purchase.

Frequently Asked Questions

What are oil additives?

Oil additives are chemical compounds that improve the performance of base oil in your cars engine. Oil additives have two functions: to prevent corrosion of the metal that forms the engine and to ensure everything within the engine is operating efficiently and smoothly. 

How do oil additives work?

Oil additives work by blending into the existing motor oil in the engine of the car, they lubricate everything that the oil touches reducing friction and providing protection to all the metal surfaces within the engine, therefore reducing the likelihood of rust or corrosion. 

Do older engines need thicker oil?

Engine oil is highly reactive to the environment so it is often questioned whether or not you should use thicker oil for an older engine.

The answer is that its dependent on your car, the best way to find out is by checking your car’s current oil pressure and comparing it with the oil pressure when your car was new. If the oil pressure has lowered then you could use a thicker oil if you wish.  

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