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Maintaining a car’s engine can feel complicated, but one simple tool many people use is an oil additive. These products are designed to go into your engine oil and help improve how your engine runs. Oil additives can reduce friction, help clean out build-up, and sometimes even protect against wear or leaks over time.

The benefits you get from an oil additive can depend on what your car needs. Some are meant to help older engines run smoother, while others are made to break up sludge and keep engines cleaner. There are also additives for specific problems, like reducing oil burning or quieting noisy engines.

When looking for the best oil additive, it is important to pay attention to your engine’s needs and what the product is made to do. Make sure it is safe for your car’s specific type of oil and engine. It also helps to check that the additive won’t void any warranties or cause future problems with seals or sensors. Choosing the right oil additive can make it easier to keep your car running well for a long time.

Best Oil Additives

We have researched and tested the top oil additives available. Our list below features products we believe can help improve engine performance and protect your vehicle’s engine parts.

Prolube Oil Treatment (paid link)

This is a strong choice for anyone looking to improve engine performance and quiet noisy start-ups.

Pros

• Designed to reduce engine noise and vibration
• Helps save fuel by minimising friction
• Works with both petrol and diesel engines

Cons

• Only enough for a single treatment in the bottle
• Some may find the price high compared to rivals
• Not everyone experiences noticeable results

Prolube Oil Treatment stands out for its promise to tackle engine noise and smooth vibrations. Many will appreciate its compatibility with various engine types, so it suits cars, trucks, and even industrial equipment. The application process is straightforward, eliminating much of the hassle from adding it to our routine maintenance.

We like that it not only aims to make engines quieter but also tries to boost fuel economy by decreasing friction. This may help vehicles run more efficiently, which is important for older engines or high-mileage cars. It also offers flexible dosing, adjusting for standard or heavy-duty needs.

On the other hand, the single-treatment size means regular users might need to buy several bottles to keep up. While some users have reported noticeable improvements, others have seen little to no change. The higher price tag could also put some buyers off, but for those seeking less engine noise and potential savings at the pump, Prolube Oil Treatment (paid link) is worth a look.

BestLine Nano-Lubricant Engine Oil Additive (paid link)

Those looking to boost engine protection and decrease friction across a wide range of vehicles should consider this high-tech additive.

Pros

• Significantly reduces engine friction and noise
• Compatible with petrol and diesel engines of all types
• Can extend oil change intervals in many situations

Cons

• Price point is higher than some standard additives
• Overuse may offer diminishing returns
• Not all shipping packaging may meet expectations

With the BestLine Nano-Lubricant Engine Oil Additive, we find a product engineered to enhance engine smoothness and performance. Its diamond nanotechnology aims to polish and protect metal parts, leading to less friction and quieter operation. This additive suits not just cars, but motorcycles, trucks, and even older engines.

One helpful aspect is its compatibility with both petrol and diesel powertrains, making it a versatile option for a range of drivers. The formula is designed to clean existing deposits while helping to prevent new ones from forming between oil changes. Users may appreciate that it works in modern engines as well as older high-mileage vehicles.

Cost is higher than basic oil additives, so it makes the most sense for those who want more advanced protection or are maintaining valuable engines. While many claim positive results, it is important to use the product as directed for best outcomes. For those seeking advanced engine care, BestLine Nano-Lubricant Engine Oil Additive (paid link) presents a confident choice.

Liqui Moly Cera Tec Oil Additive (paid link)

We think Liqui Moly Cera Tec is a sensible buy for anyone wanting to extend engine life and enhance overall engine smoothness.

Pros

• Offers effective ceramic-based wear protection
• Reduces friction and engine noise
• Works with both petrol and diesel engines

Cons

• Not suitable for vehicles with wet clutches
• Costs more than some basic additives
• May require more than one bottle for larger engines

Liqui Moly Cera Tec stands out due to its advanced ceramic technology, which forms a protective layer in the engine. This layer helps to minimise direct metal contact, reducing both wear and friction. The result is potentially quieter and smoother engine operation.

We like that this additive is compatible with a wide range of motor oils and does not interfere with typical oil filters. It’s also suitable for various components like transmissions and pumps, which adds some versatility. Fuel savings and extended engine life are positive aspects worth noting.

However, this product isn’t intended for use with wet clutches, so it won’t work for every car. It’s also relatively expensive compared to simpler oil additives and may require several bottles for large-capacity engines. Overall, Liqui Moly Cera Tec delivers solid value for those seeking an additive that offers more than just basic lubrication.

Lucas High Mileage Oil Stabiliser (paid link)

We think this is a useful option for anyone looking to help an older engine run smoother and quieter.

Pros

• Helps reduce engine noise and wear in high-mileage vehicles
• Can increase oil pressure, supporting engine health
• Works in both engines and gearboxes

Cons

• Cost is higher than average oil additives
• May not be suitable for modern engines with strict oil requirements
• Some users report the check engine light on certain vehicles

Lucas High Mileage Oil Stabiliser is made for those of us with older cars or trucks that could benefit from some extra engine support. Its thick formula helps protect internal parts, making it a choice for increasing engine life and reducing noise. This additive is also effective in gearboxes, which adds to its flexibility.

Many drivers turn to this product to get rid of engine ticking and smooth out performance. It can raise oil pressure, which is helpful if we’re noticing drops over time. The blend aims to keep engines running quiet and reduce oil consumption, especially in worn engines that are showing their age.

On the other hand, it comes at a higher price than some alternatives, so we do pay for the premium blend. Not every vehicle benefits; certain newer engines, or those sensitive to oil types, could even show warning lights after use. Still, for us with ageing engines and typical high-mileage issues, Lucas High Mileage Oil Stabiliser may be a strong pick.

Archoil AR9100 Oil Additive (paid link)

We think the Archoil AR9100 Oil Additive is a strong choice for drivers who want to improve cold starts and address injector issues in Power Stroke engines.

Pros

• Helps resolve cold start and injector problems, especially for Power Stroke diesel engines
• Designed to reduce engine wear and extend component life
• Works with both petrol and diesel vehicles

Cons

• May not deliver dramatic results for all engine types
• Some users might find the price a bit high compared to alternatives
• Benefits may be less noticeable in newer engines with no issues

The Archoil AR9100 Oil Additive stands out for its ability to help with cold start issues and common injector problems, especially in 6.0L and 7.3L Power Stroke engines. By targeting stiction and reducing friction, it supports a quieter and smoother ride for many users with older or high-mileage vehicles.

This additive can be used in both petrol and diesel engines, along with other systems like gearboxes and power steering. Its flexibility means we can use a single product for multiple maintenance needs without keeping several bottles on hand.

While the AR9100 is well-suited for those trying to fix known issues, we should note that some drivers of newer or problem-free engines might not notice dramatic differences. The cost may also be on the higher end, but for those dealing with start-up problems or injector sticking, it could be worth considering.

Liqui Moly MoS2 Anti-Friction Engine Treatment (paid link)

For drivers seeking noticeable noise reduction and smoother engine operation, this oil additive is a practical option.

Pros

• Can noticeably quiet engine noise
• Tends to promote smoother running, even at higher RPMs
• Simple to add with a single pour into oil

Cons

• May temporarily darken fresh oil
• Possible limited improvement in older, very worn engines
• Only available in one can size, which may not suit all needs

Liqui Moly MoS2 Anti-Friction Engine Treatment is designed to create a protective layer over internal parts, helping reduce friction and wear. It comes in a 300 ml can and can be used with a range of vehicles, including older engines that may benefit from extra care.

Many users appreciate how easy it is to add the treatment to their oil. Once in use, it often delivers a quieter and more stable engine operation. Some notice a drop in engine vibration or a steadier idle, particularly on cold starts.

One drawback is that the additive can make new oil look darker more quickly than usual. Results can also vary depending on engine condition—while many benefit, very worn engines may not see dramatic changes. Overall, we find it’s a straightforward and reputable choice for boosting engine smoothness and longevity.

Bar’s Leaks OS-1 Oil Seal Additive (paid link)

For those looking to address oil leaks and burning without expensive repairs, this additive offers a straightforward option.

Pros

• Can reduce oil leaks and burning in many engine types
• Compatible with petrol, diesel, and hybrid vehicles
• Simple to use with standard oil changes

Cons

• Does not work for engines losing over one quart of oil a day
• May require ongoing use at each oil change
• Results can vary depending on engine wear

Bar’s Leaks OS-1 Oil Seal Additive is designed for drivers dealing with oil leaks and blue exhaust smoke. It is compatible with a wide range of engines, including high-performance and hybrid models, which makes it a versatile choice. The product is simple to apply and can be added during a regular oil change. This can save both time and hassle for those not wanting to take the car to a shop.

Our research shows some users report reduced leaks and improved seal performance, especially in older vehicles where gaskets and seals have started to wear out. It is also suited for use in many types of vehicles and equipment, from cars and trucks to tractors and motorcycles. This broad compatibility is useful if we have more than one vehicle with similar issues.

However, it’s important to mention that Bar’s Leaks OS-1 will not help if the engine is burning or leaking large amounts of oil every day. Some situations might require regular application for consistent results, and not everyone sees improvements. For engines with serious mechanical problems, a professional repair may still be necessary.

Hot Shot’s Secret Stiction Eliminator (paid link)

This oil additive makes sense for those of us looking for better engine cleanliness and performance, especially if stiction or injector issues are a worry.

Pros

• Supports smoother running by lowering stiction and cleaning injectors
• Works in both petrol and diesel engines, adding versatility
• Can help bring back lost performance in older vehicles

Cons

• May not solve all engine issues, especially if problems are unrelated to stiction
• Some might find the price a bit high compared to standard additives
• Results can take time, so we need to be patient

We find Hot Shot’s Secret Stiction Eliminator is known for addressing stiction problems in injectors, which can affect how smoothly an engine runs. Its cleaning action supports a quieter engine and might extend its life by reducing wear. This could be a solid option if we drive older vehicles or diesel engines that use HEUI injectors.

It helps clear away residues and lubricates engine parts, making it a helpful maintenance step between oil changes. The formula is tested and can reduce wear in the engine, which should help keep things running better for longer.

While the product is versatile, working with many engine types, it is not a quick fix for serious mechanical failures. It’s important for us to use it as directed and be realistic about what it can achieve on its own. If we are after better engine reliability and don’t mind waiting a bit for results, this additive makes good sense.

Rislone Engine Treatment Concentrate (paid link)

We should consider Rislone Engine Treatment Concentrate if we’re looking to help reduce engine noise, prevent sludge build-up, and improve overall engine performance.

Pros

• Helps keep engine parts cleaner by removing sludge
• Can quiet noisy lifters and valves over time
• Designed to work at a wide range of temperatures for better protection

Cons

• Some users may not notice immediate results
• Thinner consistency than some people expect
• Price is a bit higher compared to other oil additives

Rislone Engine Treatment Concentrate focuses on cleaning out harmful deposits in our engines while helping to lessen friction and wear. It offers a straightforward approach to maintaining engine health by targeting build-up that can clog oil passages or stick piston rings.

Some drivers might notice lifters or valves becoming quieter after adding this to their oil, especially if noise has been a problem before. It is also built to perform whether the engine is hot or cold, which gives us a bit more peace of mind in different environments.

However, there are a few things to weigh up. While some people notice improvements right away, others report little or no visible change. As the formula is thinner than similar products, it might not meet everyone’s expectations for consistency. The cost is also a bit higher than basic additives, so we’ll want to decide if the benefits match our budget.

REV X Zinc Oil Additive (paid link)

Those of us with classic cars, older engines, or any flat tappet setup looking for extra protection may want to consider this additive for its anti-wear support.

Pros

• Adds a layer to prevent metal-on-metal contact
• Suitable for engine break-in on older or rebuilt motors
• Works with both synthetic and regular oil

Cons

• Best results are mostly seen in older engine designs
• Only comes in a small 2-ounce bottle per treatment
• No instant results, as benefits are long-term

This additive from REV X focuses on protecting camshafts and lifters, especially in engines that need more zinc and phosphorus. It is often recommended for break-in periods or for use in classic cars where extra wear can be an issue. Many users appreciate that it can be mixed with various types of engine oil.

We like that it works in both synthetic and mineral oil, which means it fits a wide range of vehicles and equipment. The anti-wear coverage from ZDDP is useful for engines under heavy loads or for machines where high pressure is a concern. With regular use, it can help reduce the risk of cam and lifter wear, though this is most valuable in engines designed before newer oil standards reduced zinc content.

It is important to note that improvements take time, and the real benefit is seen over the long haul. It won’t fix existing engine problems, and some might find the small bottle doesn’t go far for larger engines. However, for those maintaining classic motors or anything with flat tappet cams, REV X Zinc Oil Additive (paid link) could be a straightforward option to help safeguard engine parts.

Buying Guide

When choosing oil additives, we should focus on the type of vehicle and oil we use. Not all additives work with synthetic, diesel, or high-mileage oils. Let’s check the product label to see if it fits our engine.

We want to look at key features such as:

• Purpose (cleans, reduces wear, prevents leaks)
• Compatibility (engine type, oil type)
• Ease of Use (pour-in, mix, frequency)

A simple table can help us compare options:

Feature	What to Look For
Engine Compatibility	Petrol, diesel, high mileage, synthetic
Function	Cleaning, sealing, lubrication, anti-wear
Additive Type	Liquid, treatment, sealant
Application	Easy to add, frequency of use

We need to check for any warnings or requirements in the instructions. Some additives may need us to change oil sooner or use them only with fresh oil.

It helps to read reviews from other users who have a similar vehicle. Their experience may guide us in choosing an option that suits our needs. We should also buy from a trusted shop to avoid counterfeit products.

Price is a factor, but we should balance cost with the benefits each product offers. Buying the cheapest additive does not always save us money if it does not protect or improve our engine.