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8 Best Oil Additives – (Reviews & Buying Guide 2021)

It is a commonly known fact that engine oil is a crucial ingredient for all smoothly running engines. It lubricates moving parts and plays an essential role in how well your engine performs. However, just like with other engine elements, it is possible to boost its performance.
This is where the best oil additive comes to help. This product enhances the existing positive elements found in your engine oil and suppresses all the negative traits that you may encounter in certain performance situations. Engine oil additives are a simple, cheap, but at the same time, highly efficient engine upgrade.
There are many oil additives available on the market, and finding a high-quality one may not be that easy. That’s why in our buying guide you will not only find a lot of useful tips and info but also reviews of oil additives that we believe will make your engine work as good as new.

Best Oil Additive Reviews

1. Liqui Moly 2009 Anti-Friction Oil Treatment

Liqui Moly 2009 Anti-Friction Oil TreatmentLiqui Moly is a brand that offers a global range of automotive chemicals. It manufactures products exclusively in Germany, and the Liqui Moly Anti-Friction Oil Treatment was just another one of its products that we were delighted with.
The difference this oil additive makes is quite noticeable even in the first few days of use. Your engine will stop sounding like it is starting dry. We also noticed that at startup, the engine RPM started spiking higher than before, and there was pretty much no noise. The one thing that we did not like is that the bottle is only 300ml.
The oil additive forms a high load-bearing film of lubricant on all friction surfaces, and you will definitely be surprised at how better your engine will sound and how controlled it will be. However, this product does not really increase the MPG. Other than that, our team believes that this oil additive is an excellent choice for your vehicle. Just be careful, as it is still a chemical and prolonged or repeated contact may cause your skin to dry.


  • The engine sounds better
  • Forms High load-bearing film of lubricant
  • Affordable


  • Does not cause a change in the MPG
  • Small bottle

2. BestLine Premium Synthetic Engine Treatment

BestLine Premium Synthetic Engine TreatmentThis BestLine 853796001049 Premium Synthetic Engine Treatment is an advanced oil treatment that will treat, clean, and protect all internal engine components. The results may not be seen immediately, but trust us they are there. Your engine will be coated with an ionically bonded layer of lubricant that reduces heat, wearing out, and friction. At the same time, oil additive increases fuel economy and provides better engine performance.
The BestLine 853796001049 Premium Synthetic Engine Treatment is a unique 100% pure synthetic metal treatment and is compatible with all motor oils. This product does not only reduce harmful emissions but also reduces and virtually eliminates noise and wear.
The oil additive comes in a 16-ounce bottle. However, we were disappointed to notice that in reality, there was only 12-13 oz in it. This is important as you may need precisely 16oz for your car, and in the end, you will have to get 2 bottles. The fact that this product is a little pricey does not help at all. However, the unit is indeed useful.


  • 100% pure synthetic metal treatment
  • Compatible with all motor oils
  • Reduces harmful emissions
  • Reduces heat, wear, and friction


  • The bottle says 16 oz, but there is only 12-13 oz in it
  • A little pricey

3. REV-X Stiction Fix Oil Treatment

REV-X Stiction Fix Oil TreatmentThe REV-X Stiction Fix Oil Treatment is an oil additive that can ramp up the performance of any lubricating fluid, without using any harmful additives. This product provides extended service life for all lubricating fluids, and for the price, you even get two bottles.
Now, there are two main things that we believe can be a problem. The first one is the price. Compared to other oil additives, this one is a bit more expensive. However, it is highly effective, and you get two bottles instead of one. The other problem, however, is the size of the containers. Yes, they are two, but they are relatively small. Of course, we must mention the fact that the product is highly concentrated and you can treat up to 12 quarts of oil using the two bottles.
We like the fact that the REV-X Stiction Fix Oil Treatment quiets engine noise while cleaning harmful deposits, sludge, and varnish. It will also eliminate cold start issues in all diesel engines. Another great thing is that you could use this product in any engine- snowblower, lawnmower, car, truck, SUV, etc.


  • Increases efficiency
  • Increases horsepower and torque
  • Quiets engine noise


  • A bit more expensive than other oil additives
  • Really small bottles

4. Archoil AR9100 Oil Additive for All Vehicles

Archoil AR9100 Oil Additive for All VehiclesThe Archoil’s AR9100 oil additive is suitable for use in all gasoline and diesel engines. It forms a solid boundary film that will protect your engine, gearbox, and hydraulic system. The product will also eliminate cold/hard start issues, and your engine will work as a brand new one under the most extreme conditions.
The Archoil AR9100 Oil Additive reduces friction, and that means that your system will develop less heat and run quietly and smoothly. We like the fact that the product comes in a 16-oz bottle, and even though you may have to wait a bit before you see some results, you will be able to use the product a couple of times and save some money.
This oil additive can remove and disperse any varnish, sludge, and carbon deposits that have built up in your engine. However, when it comes to MPG increase, you may be a bit disappointed as there is no visible difference. Bear in mind that this unit works perfectly with gasoline and diesel engines, power steering systems, hydraulics, gearboxes, and differentials.


  • Less heat
  • Prevents sludge and varnish deposits
  • Extends oil drain intervals


  • Does not cause any noticeable MPG increase
  • You may need a couple of weeks to notice the difference

5. XADO Engine Oil Additive

XADO Engine Oil AdditiveWe liked the XADO Engine Oil additive as it provides active protection against overheating and overload. This is an innovative 3-component oil additive that is specially formulated for repairing essential engine parts in cars with oil system capacity that is up to 5qt. Due to the Revitalizant this oil additive has, it can reduce friction, rebuild metal, and create a protective coating against future wear.
Another great thing about this product is that one treatment can last for 60,000 miles. However, we noticed that this oil additive does not help with the noise your engine might produce. On the other hand, it lowers fuel consumption and increases power and acceleration.
Since this product is highly effective, it is also a bit more expensive than most oil additives on the market. We also would have liked it even more if it came in a bigger bottle. Other than that we were delighted with the results the XADO Engine Oil additive gave us.


  • Reduce exhaust emissions toxicity
  • Increases engine cylinders’ compression
  • Reduces fuel consumption


  • Does not help with the noise
  • The bottle is too small for the price
  • It is suitable only for cars with oil system capacity up to 5 qt

6. ZDDPPlus ZDDP Engine Oil Additive Zinc & Phosphorus

ZDDPPlus ZDDP Engine Oil Additive Zinc & PhosphorusWhat we like about this oil additive is that it contains high concentrations of the well-known additive ZDDP (Zinc Dialkyl Dithiophosphate). This has been the primary EP ingredient in all quality motor oils for more than 70 years.
The ZDDPPlus ZDDP Engine Oil Additive Zinc & Phosphorus alters bearing and journal surface characteristics and prevents metal to metal contact. The other thing we liked is the fact that this product is compatible with all synthetic and conventional oils that are intended for automotive use.
This oil additive is also easy to use. The only thing you need to do is add the entire 4-oz content of the bottle to a 4 to 6-quart oil change. This product may seem a bit expensive but is highly effective, especially for older cars with flat tapped lifters-cam that need an added zinc protection. However, we didn’t notice any change in the MPG when we used the product. Bear in mind that this oil additive is meant to be used on pre-1989 and high-performance engines.


  • High concentrations of Zinc Dialkyl Dithiophosphate
  • Compatible with all synthetic and conventional oils
  • Protects the engine


  • May seem a bit expensive to some people
  • Does not increase MPG

7. Rislone 4405 Engine Oil Supplement Concentrate

Rislone 4405 Engine Oil Supplement ConcentrateThe Rislone 4405 Engine Oil Supplement Concentrate with Zinc Treatment does not only do a great job when it comes to helping the engine but is also one of the cheapest, yet still effective, products available on the market. Rislone is a well-known brand with over 90 years of experience, so you can be sure that this product will give your car a fighting chance at a healthy, long life.
We liked how well this product cooled and lubricated the moving parts of the engine. The special additives the Rislone 4405 Engine Oil Supplement Concentrate with Zinc Treatment has, prevent oil thinning at high temperatures. This product also creates a sacrificial layer on the components where metal to metal contact happens, and that way, it prevents the metal itself from getting worn.
Keep in mind that this oil additive is not suitable for new cars and should not be used on vehicles with catalytic converters. This product is not only an anti-wear additive but also a corrosion inhibitor. However, it does not help with the irritating noise some older engines may produce.


  • Uses zinc and phosphorus
  • Prevents oil thinning
  • Prevents metal from getting worn out


  • Not suitable for vehicles with catalytic converters
  • Does not help with the noise

8. AI Innovations LUC10002 Lucas Heavy Duty Oil Stabilizer

AI Innovations LUC10002 Lucas Heavy Duty Oil StabilizerThis AI Innovations LUC10002 Lucas Heavy Duty Oil Stabilizer is an excellent option for worn engines that are not entirely sealed up. It is a heavy-duty product that you will surely be pleased with as your vehicle will go from constantly sputtering oil after the engine had warmed up, to finally holding oil pressure. If you want to keep your older engine running smoothly than this is your product. However, if you plan to use it on a new engine, we recommend that you look for a different oil additive.
The AI Innovations LUC10002 Lucas Heavy Duty Oil Stabilizer does not only reduce oil consumption, but it also increases oil life with at least 50%. On the other hand, our team noticed that the product does not really help with the lifter noise, and many people look for oil additives for that reason, so bear that in mind.
Another great thing about it is the fact that it comes in a 1-gallon bottle, so you will be able to use it many times.


  • Reduces oil consumption
  • Reduces oil life with around 50%.
  • Highly effective
  • 1-gallon bottle


  • Does not really quiet the lifter noise
  • Not suitable for new engines

Oil Additive Buying Guide

You just got through our list of select oil additives, but now it is time to go through some general information about them. Our work will make your decision even easier, and you will know what these products can do, how to use them, when to use them, and more.

Factors to Consider When Looking for an Oil Additive

  • Best Oil AdditivesRust prevention

    This is something every additive should be able to do. Rust makes a big mess on the inside of your engine, and it can stop the parts from moving. It also makes it difficult for the pistons to function. Due to this, you will hear noises while driving. Initially, the sound won’t be that strong, but over time, it gets worse.
    To prevent all that, you need a product that cleans the oil passages, removes sludge and dissolves rust. The best products in this class will keep the chemical vapors from forming sludge and rust even in high temperatures.

  • Climate adaptability

    People know that they can use additives either during summer or winter, but not all supplements are suitable for below-zero temperatures. Interestingly enough, there are some additives which don’t work well when exposed to high temperatures, because they start degrading. When looking for a high-quality car oil additive, it should be one that can cope with both hot and cold environments, without losing any of its powers or performing differently.

  • Friction reduction

    The engine pushes metal against metal and creates friction. This is the basic operation of any engine, yet it can still cause problems. You can have too much resistance, which will make the metal parts chip away, and get damaged.
    The right amount of oil and the right brand, of course, will reduce friction and noise. For this, you have to look for products that can create a protective layer around the metal parts. You can even get a product which will stick to the pistons, thus eliminating any knocking noise.

  • Increase miles per gallon

    As weird as it may sound, oil additives can improve your miles per gallon. It’s not hard to reach this conclusion, though. If your engine runes smoothly this means that it will also require less fuel to run for longer.
    Needless to say, not all oil additives will do the trick. You need a product that will eliminate dry starts and that will raise the pressure of the oil within the engine. More often than not, these additives are called oil stabilizers

  • Viscosity

    Most of the time, people buy a thicker additive. However, you should always consider what product will work properly with your engine. What will help you decide is looking at how narrow or broad the oil passages are or if you have a small lifter with small opening and valves. This will show if you need a thin or thick product. Narrower engines require a light liquid, while if you have an engine with more extensive openings, you will need a more viscous liquid to flow through.

  • EPA Certification

    Cars emit harmful emissions – this is clear as day. However, you can reduce them, thus improving your fuel economy. It’s a win-win situation. If you look for oil additives with an EPA certification, you will get a supplement that doesn’t contain any harmful substances. This is the best environmentally-friendly additive you can get on the market nowadays.

  • Engine Model

    It is important to always look at the label of the additive which indicates the type of engine the oil is for. Engines require different motor oils and this also calls for the use of various additives. Each motor oil has a so-called specification. This specification is designated by a little code on the label of the bottle. Various oil additives fit only certain oil specifications. In short, not every additive is for every engine.
    This is why it’s essential to look at the label. In case you don’t know what type of engine you have, you can look at your car’s manual and it should be included there. Then you can choose an appropriate oil additive which will be compatible with your car’s engine. Some people do ask themselves, ‘Why would I upgrade to synthetic motor oil’? Well, for starters – synthetic oils are compatible with a broader range of oil additives.

Types of Oil Supplements

Of course, there is more than one type of oil additive. But don’t get discouraged, we will talk about the main ones here. Let’s get started!

  1. Engine oil stop leak – As the name suggests, it is used mainly for stopping any leaks in the engine. No matter how tightly the engine has been put together, leaks are to be expected. This type of oil additive will stop the oil from leaking through the gaps between the engine walls.
  2. Engine break-in oil supplement – It helps protect the camshaft lifters in the car, and it can lubricate the valve train. This means it can also be added to the group of Lubricant Additives. This additive is good when your car is brand new and the engine hasn’t been used yet.
  3. Massive duty oil stabilizer/Antioxidants – If you need friction protection, you might want to consider this.
  4. High mileage oil stabilizer – another type of additive that is easy to guess from the name. It is excellent for this old engine that you still use.
  5. Complete Engine Treatment – This is great for preventing friction. It can form a protective barrier around the engine parts but will also eliminate any heat in excess.
  6. Detergents – This type has an alkaline nature. It means you can use such products to lower the acidity level of the engine oil and ward off unwanted deposits that can grow in high temperatures. A fine additive when you want to get rid of some organic impurities.
  7. Anti-foaming agents – You might not be aware of this, but sometimes your engine oil produces air bubbles. An anti-foaming oil supplement will burst these bubbles. If that doesn’t happen, the bubbles can speed up the oxidation process, which in turn leads to corrosion.

Another good product related to the maintenance of your engine and exhaust system is the catalytic converter cleaner. While it operates on the other side of the system, it is still a valuable component of your vehicle’s maintenance. Make sure you check out our article and reviews on that product. You may also like: catalytic converter cleaner buying guide

How Does an Oil Additive Work?

How Does An Oil Additive WorkThe performance of the oil is measured by its thickness or the so-called viscosity. If it’s too opaque, it will block your engine. Too runny and it will run like water, missing its mark. Here is where oil additives come in place. They improve the viscosity, so your engine can perform well. However, know that your oil’s viscosity is affected by temperature as well as by some external (weather conditions such as a bad snowstorm) and internal (a piping hot engine block) factors.
Oil additives help with all these things. They are even known to prolong the life expectancy of motors. This happens because such products can optimize the use of the motor. Some vital things for your engine are temperature regulation and fluid use of all moving parts.

Signs that Your Vehicle Needs Additives

  • Oil viscosity – We mentioned that thickness is something significant for the oil and that additives can help with it. For this reason, you need to regularly check if your oil is too thick or runnier. If that’s the case, then you may need to use an oil additive.
  • Engine’s temperature – Technically, the heat comes from fuel combustion. However, the friction of parts inside of the engine also plays a role. Once you reduce the friction, then the temperature goes down as well. The best type of product to use for that matter is the cutting oil additive.

When to Change or Add Oil Additives

Because you pour the oil additive in your engine oil, that means that every time you change the oil, you will need to add the additive as well. If you require new oil, you can look at some good synthetic oil reviews, where you might be able to find your engine’s next oil. Our team has devoted an article especially to them.
When it comes to pouring some additional product to the oil, it’s a bit tricky. You shouldn’t do that because oil additives are meant to be mixed with the oil upon oil change. However, if you notice that the viscosity of your oil is sort of letting up, feel free to add a little bit of product. All in all, avoid putting in extra oil additive unless you have to.

Benefits of Using Oil Additives

Oil Additive ReviewsSome of the benefits and things that oil additives can do may differ depending on the type you want to get, but here are some of the advantages these supplements can offer.

  • Improves engine performance.
  • Prevents so-called ‘oil firm break’.
  • They can reduce the friction of engine components.
  • Prevents any build-up of sludge.
  • Can prolong the life of engine components and engine oil.
  • The additives are compatible with both synthetic and mineral engine oil.
  • Reduces any foaming around the crankshaft.
  • Can prevent metal surfaces from becoming rusty.
  • Regulates temperature.
  • Reduces engine oil loss and noise. This is a widespread reason why people get this product.
  • Many are trying to find a high-quality oil additive for a quiet engine.

Difference Between Oil Additives and Fuel Additives

Radiator additives, oil additives, and fuel additives have one thing in common: they are all added with the purpose to improve the properties of a certain fluid. However, these fluids are different
Oil is used to lubricate the engine, thus allowing it to run. Therefore, oil additives only help your engine to perform better- no noise, no cold starting, no overheating, etc. Fuel additives, on the other hand, are used to improve the octane rating of the fuel because they contain corrosion inhibitors for parts that exist in your fuel. That means that their primary purpose is to increase your miles per gallon or in other words, the fuel efficiency.

Chemicals in The Additive

There are 2 main chemicals in oil additives that deserve our attention. Both of them have many positive effects on the functionality of additives. Excessive amounts of those chemicals, however, can have a degenerative effect.

  1. Zinc –This acts as a performance booster. It’s especially helpful for older engines.
  2. Phosphorous – This is something you want to look for in an additive if you want it to deal with metal-to-metal friction between the elements. This will directly prolong the engine’s life.

Needless to say, there are blends between phosphorous and zinc so looking for an additive that has them both is a good idea.


  • Q: Can I mix some synthetic oils with mineral ones?
    A: It is possible to do. Nevertheless, the quality of the mixture will be affected accordingly. It will be either may either improve or worsen, so keep that in mind.
  • Q: Can two oil supplements be used at the same time?
    A: Most of the time, you can do this. However, always check if there will be any negative effect on either of them or the whole mix. We recommend that you are sure what you’re doing when undergoing such endeavors. Becoming familiar with most high-end car maintenance products will surely be beneficial to you so check out our other articles.
  • Q: Can Oil Additive or Engine Protect be used on motorcycles as well?
    A: Engine Protect isn’t recommended for use in wet clutches. But at 20ml of additive per 1 liter of engine oil can have a beneficial effect on wet clutches and even prevent clutch slip.
  • Q: Are there benefits of using a particular diesel engine oil?
    A: Soot is the biggest problem of diesel engines. Such oils possess powerful “cleaning” properties, which prevent buildup. It is recommended that you strictly use diesel oil and the respective additive if that’s the type of engine you have.

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Wrap Up

There you go! That’s the complete guide on getting the best oil additive for your engine. You now realize how essential it is to find a high-quality product that will increase the power of your engine and prevent sludge and varnish deposits. To do so, the only thing you need to do is read our reviews of oil additives and choose a product.
If you think that our piece has been useful, make sure you share it with all your friends, they may find it helpful as well. Also, if there is anything you would like to ask us, do not hesitate to pop us an email or leave us a comment in the comment section.
We have other buying guides devoted to finding the right unit. Just find some time, and go check them out as well. Thanks for reading, and as always- stay put!