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Best Engine Oil Stop Leak Additive – What Is The Best

February 25, 2019 By John Smith 7 Comments We are reader-supported. If you buy through links on our site, we may earn a small commission.

NameSpecial FeaturesSizeOur Raiting
Lucas Oil 10278Best All-Around32 ounces4 stars Check Price
ATP AT-205Best Budget 8 ounces4 stars Check Price
BlueDevilFor Experimenting5 ounces3.5 stars Check Price
Bar’s LeaksFor Rear Main Seal17 ounces3.5 stars Check Price
NO LEAK 20401For Engine Gaskets16 ounces3 stars Check Price
Best Engine Oil Stop Leak AdditiveAdding the stop leak additives to your engine oil is one of the easiest and the most convenient ways of stopping engine oil leaks. The application is simple, painless and effortless, and the is often very affordable. But, this is all true only if you pick the right product, of course.

To do that, you will first need to inform yourself about the product category and to examine specific product’s strengths and weaknesses.

Best Engine Oil Stop Leak Additive – Reviews

In this article, you will find two things: first is the list of top 5 products (anti-leak additive), and a second is our Buyer’s Guide.

In this guide,  we will give you some advice and direction as to which the best engine oil stop leak additive you should buy, should you buy it, what things you should worry about, and how long can you depend on the oil leak additive. Now lets’ get to work, shall we?

Lucas Oil – The Best Engine Oil Stop Leak Additive

Lucas Engine Oil Stop Leak
More Pictures

Lucas Oil 10278 is the most expensive, but also the most effective item on our list. It is compatible with all types of engine oil (petroleum, and semi or full synthetic engine oils).

The product is purchasable in 1 quart, 1 gallon, and 55-gallon packages; of course, the greater package you buy, the better deal you make.

Lucas stop-leak oil is safe to use, promising to revive deteriorated seal and not cause any damage to your engine. In fact, Lucas Oil should (as a consequence of successful sealing), reduce engine noise and oil consumption. But does Lucas anti-leak oil keep its promises?

According to many customers, yes, Lucas Oil 10278 does deliver. It is a one-time deal; you have to pour at least 80% of standard oil (at least), and then you add you no more than 20% of the anti-leak oil (which is the maximum amount allowed by manufacturer’s instructions). And that’s it; that’s how you apply all other oils.

Lucas stop-leak should work on first application; it does, for most people. Those who have minor leaks have reported that the Lucas oil either stopped the leaking completely or partially (slowed down the leaking). Why didn’t it work for everyone? Well, that depends on the damage.

If the damage is extreme, Lucas stop-leak oil won’t help you; no oil will help you. For severe mechanical damage, you need a mechanical solution, not chemical. Fortunately, Lucas Oil 10278 does work on minor leaks and doesn’t contain harmful chemicals for your engine, which is what you should be looking for in every stop leak oil.

If the first application doesn’t work for you, try adding another patch, but monitor the situation. If it doesn’t improve with time (if the leaks don’t slow down or stop), seek a mechanic.


Pros
  • fixes minor damage
  • doesn’t harm the motor
  • cost-effective (larger quantities cost less)
  • reduces oil consumption and engine noise
  • renews worn seals with no risk of damage or eventual corrosion
  • contains no harmful solvents
  • compatible with petroleum, semi-synthetic and full synthetic motor oils
Cons
  • the most expensive product

AT-205 ATP Re-seal Oil – The Best Budget Engine Oil Stop Leak Additive

AT-205 ATP Re-seal Oil
More Pictures

AT-205 ATP works with gasoline and diesel engines and can be purchased in 2 or 4 packs (1 bottle has 8 oz). AT-205 ATP works rapidly and effectively, sealing the leaks. It should, in theory, heal every rubber seal on your engine.

AT-205 ATP also stops leaking in other systems, including transmission, hydraulic and power steering system. It is compatible with all oils, conventional and synthetical (synthetic and fully synthetic). It has no chemical distillates, and will not break the existing seal (but re-seal them).

According to manufacturers instructions, one 8 oz bottle should be enough for six qt capacity. For best results, adjust the formula to your vehicle’s capacity (don’t overuse it). Also, you must know that you can’t use this oil on brakes.

AT-205 ATP’s formula focuses on reshaping and fixing rubber based gaskets and leaks. It consists of plasticizers, a chemical that is also used in the manufacturing process of rubber gaskets and seals, to adjust their flexibility.

So when your only defense mechanism loses its flexibility over time (because the plasticizers lose their effectiveness), the AT-205 ATP rejuvenates the rubber and prevents or stops the leaking. Just pour it as you would engine oil, and monitor results.

How long does it take to work? According to the manufacturer, it can take up to five hours before it starts working. You can add it at any point between oil changes, and no preparation is required. And remember, you can use it on any vehicle, even if it uses specialty fluid type.

If the rubber seals and gaskets are severely damaged or cracked, the AT-205 ATP will not stop the leak. It will do an excellent job at a very affordable price.
Pros
  • works rapidly and effectively
  • contains plasticizers, which help repair rubber seals and gaskets
  • very cost-effective
  • doesn’t contain harmful chemicals
  • compatible with all engines and oil types
Cons
  • works with minimal leaks only

BlueDevil Oil Stop Leak – The Best Oil Stop Leak For Experimenting

BlueDevil Oil Stop Leak
More Pictures

BlueDevil is hit or miss oil stop leak; it works wonders with some people and nothing with others. It is a medium priced product and comes in a can of 237 ml, roughly 8 oz. It is compatible with diesel and gasoline engines, and is non-clogging, making sure it doesn’t harm the engine.

It is safe and easy to use and will recondition and repair your hard seals at the current leak points. It fixes dripping conditions, it reconditions shrunken and hard seals and permanently repairs the damage.

You add one bottle of BlueDevil Oil Stop Leak to your engine oil and wait for the results; your oil should stop leaking after roughly 100 miles of driving. Note that you can use it for fixing gear cases, gear differentials pinion seals, and other systems. You shouldn’t use it for your brake system, or any other painted surface.
But BlueDevil Oil Stop Leak isn’t perfect. Some user said that the engine doesn’t always fix the leaking gaskets. Also, it may not work with all engines (works on both types, but not on all specific engines).

It is affordable and should work after the first application, but there’s no guarantee that it will work. Also, some have complained about the BlueDevil customer service, claiming that they weren’t very user-friendly.

We stand by what we said at the beginning; this is a hit and miss product. The good news is that the BlueDevil oil stop leak is cheap (so that you can test it), but don’t forget that it sometimes requires up to 100 miles of driving to fix the leak.


Pros
  • inexpensive
  • repairs and reconditions rubber seals throughout any fluid oil system
  • when it works, it protects the engine for a very long time
  • compatible with almost all engines
  • doesn’t harm or clog the engine
Cons
  • it requires a long time to activate
  • inconsistent results

Bar’s Leaks Seal Repair Fluid – The Best Repair Additive For Rear Main Seal

Bar's Leaks 1040 Seal Repair Fluid
More Pictures

Bar’s Leaks is the most inexpensive product on our list, available in a pack of five or six, each bottle containing 16.9 ounces. Bars Products feature many protective fluids, each for different purposes. The purpose of Bar’s Leaks seal repair fluid is to fix the oil leaking.

As soon as you notice dark spots below your vehicle, it means you have an oil leak problems. It starts slowly, but eventually, oil leak becomes bigger and bigger (like cavity on your teeth, slowly taking over).

Bar’s Leaks repair fluid engineered specially to restore engine seals and improve elasticity caused by wear, high temperatures, and harsh conditions. It also features more sophisticated polymer sealing additives. These additives prevent leaking by building a shield around the seal, thus preventing the oil from exiting through the cracks.

The first symptom of main seal leak is a sudden drop in oil reserves, according to Bar’s Leaks Products. Then, you start noticing black and brown spots on your driveway or in your garage. While the Bar’s Leaks repair fluid has been designed for fixing leaks that occur in the rear main seal, it will work on every engine oil leak.

Bar’s Leaks can be used on O rings, rubber gaskets, cover seal, and so forth. Its formula works differently from other engine oil stop leak additives; it attacks the rubber, causing it to swell and close the gaps. Now, most manufacturers are trying to avoid this behavior because, if your seal is cracked, Bar’s Leaks can do more damage than good.

You should be noticing results after you drove a couple of miles (usually after 100 miles), assuming that the product has worked for you; if the seal is cracked, it won’t fix your problems.


Pros
  • aggressive but effective formula
  • the most inexpensive product on the list
  • protective and durable
  • stops or slows down the oil dripping
Cons
  • doesn’t fill in the cracks
  • requires more than one application

NO LEAK – The Best Engine Oil Stop Leak Additive For Engine Gaskets

NO LEAK 20401 Engine Oil Stop Leak
More Pictures

Last product on our list is the NO LEAK 20401. While this product did receive mixed feedback, we still find it worth reviewing, do to its compatibility with all engines. The product arrives in one 16 oz bottle and is the second most expensive item on the list.

This oil additive inflates the protective rubber, conditioning them and improving their elastic form. It is mostly recommended for fixing rear main seals, but also promises to stop smokes, and also helps condition seals. The bottle is nicely designed, and very simple to pour.

According to the manufacturer, these are the steps you must go through:

  1. Remove the cap of the bottle
  2. Pour the fluid in the oil reservoir, but make sure you don’t overflow it
  3. Now replace the filler cap
  4. If everything works, the leaks should stop after 200 miles of driving
As you can see, it will take some time before you see the results, which isn’t good news for people who need an instant solution. While you wait for the results, much damage can be done to your vehicle. Instead, use NO LEAK 20401 Engine oil stop leak only to fix minor issues.

Because deteriorated engine gaskets often cause engine problems, NO LEAK 20401’s formula focuses on repairing them (gaskets) and is probably the best no leak additive for the job. Also, it works best as the sooner you apply it, for it also protects the rubber seal.


Pros
  • formula engineered for repairing and protecting gaskets
  • easy to apply
  • compatible with every engine
  • should remain active for an extended period
Cons
  • requires many miles to activate
  • relatively expensive

Buyer’s Guide

Now that you’ve seen the list, it is time we discuss the product category. Here, we will explain the benefits of using the engine oil stop leak additives, when to use, should you use them, and which product should you buy.

What Is Engine Oil Stop Leak Additive Anyway?

Engine Oil Stop Leak Additive is a chemical compound which contains friction modifiers and other chemically processed and refined petroleum products.

Heat, mileage, and harsh operating conditions slowly wear out the engine gaskets, O rings, and other protective seals. This problem starts naturally and grows gradually, and non a single vehicle is immune to this. It begins with small leaks but can grow into cracks and gaps.

Then, oil escapes the reservoir through the cracks, and the oil starts leaking. Leaving it be is a very dangerous thought because the hole can grow entirely out of proportions, causing significant damage to your vehicle (not to mention your wallet).

As a consequence of that, you have two solutions: you can either change the protective gaskets and seals or, you can use the engine oil stop leak additive. You follow the instructions and add an adequate amount of additive fluid just as you would ad standard oil.

Do Engine Oil Stop Leak Additives Work And How Does It Work?

Engine oil stop leak additives came a long way. At first, these additives featured a formula that would consist of clogging particles. In fact, some of the first engine oil stop leak additives were just a mixture of castor oil containing groundnut shells.

However, even though the additives were working, the formula was very harmful to the engine. It featured too many particles, which would eventually clog down the engine.

Thankfully, new formulas are much more sophisticated. Modern engine anti-leak additives work to expand and repair the gasket and seals, to regenerate the defense lines (see this Quora Discussion).

When Should You Use It?

Engine oil stop leak additives can be used quite liberally, even when the symptoms are negligible. In fact, the sooner you notice any oil-related operational irregularities, you should use the additive to not only prevent the occurrence of cracks and holes but to protect the oil reservoir for future endeavors.

Once you apply, wait for the additives to start working. If the oil continues to leak, that means two things: either the additives aren’t working, or the damage is too extreme. Most of the times people react too late and expect that the engine oil stop leak additives will fix something that cannot be fixed with chemical additives.

In essence, you should almost always use the no-leak additives to fix minor issues. But you shouldn’t choose any item; here are the things you should be paying attention to during the selection process:

Compatibility

First and foremost, make sure that the additives are compatible with your engine oil, as well as your engine type. While most products on our list are compatible with all engine types and all oil types, some exceptions may apply.

It is always best that you double check the manual, or that you contact customer service because incompatible engine oil stop leak additives might do more harm than good.

On Uniqueness (Concerning Formula)

As we showed in this article, these products feature different formulas. Some are more aggressive and respond rapidly, others nurture and regenerate. Some formulas try to penetrate deep into the pores and create a protective polymer film, others “bite” the rubber and induce swelling.

Also, some products are better for specific roles. For instance, NO LEAK 20401 is the best option for fixing gaskets, while the Bar’s Leaks 1040 repair fluid works best on the rear main seal. Alas, some of the products we featured not only stop the sealing but can also reduce noise engine and prevent corrosion, like the Lucas Oil 10278.

We advise you that you focus on the two things more than on anything else: figure out the reasons as to why you need the anti-leak additives (to prevent O rings, to regenerate gaskets, to support rear main seal, etc.) and make sure it is compatible with your vehicle.

On Activation Speed

Many people misunderstand the activation process: there is a difference between activated and fully activated fluid. Once you add the engine oil stop leak fluid, it will activate with the few hours of driving. But, they won’t fully activated before you reach the dedicated threshold.

Some products take 100 miles to activate, others 200 or more. Why is that important? Those 100 miles can make a difference between minor and significant damage done to your gaskets, or entire vehicle. If you need help immediately, don’t go for the products that feature delayed activation.

On Quantity

You should also think about the amount of oil you need. Evidently, it is always best to go via the most cost-effective route and buy the additives that work in an only a one-time application. But, sometimes you need to use the additives several times to fully regenerate the sealing rubber, no matter how good the formula is.

Your judgment should be based on the severity of the situation: if you think you will need to apply several applications, order appropriately. Monitor the situation, and see if the leaking slows down over time. If it does, it means that the formula is working and that you should continue applying it.

On Protectiveness

When we talk about protectiveness, we refer to two things: durability and broader positive implications. What does that mean? For instance, the Lucas Oil 10278 is very durable anti-seal additive: it requires one application and stops minor leaking very rapidly.

However, it does more than that. It prevents oxidation and development of rust and also reduces engine noise. On the other hand, AT-205 ATP Re-seal Oil enhances the functioning of transmission, power steering or hydraulic system: these two examples are considered as broader positive implications.

FAQ

How Is This Product Used?

The application of anti-seal additives is simple: add the fluid in the appropriate oil, and the job is done. You do have to measure the ratio between engine oil and no leak additives. Always refer to user’s manual before you start mixing.

Should I Do Any Preparation?

Well, preparation isn’t necessary, but it won’t do any harm. Some people have suggested that cleaning the engine and oil system (removing dust, debris, particles, etc.) can help the engine oil stop-leak additive, but there isn’t enough evidence to support that claim.

Still, even though the manufacturers don’t suggest you do any preparation, we recommend you do it anyway, to make sure that you did everything you could to stop the leaking.

What Should I do If The Leaking Continues?

If you aren’t that knowledgeable about vehicles, seek the help of a professional. Maybe you need to switch to another additive, perhaps you need to replace the gaskets, or your vehicle needs some serious work.

Can Engine Oil Stop Leak Additive Fix The Cracks?

It depends on the type of formula it features. Sure, additives might be able to seal small to medium cracks, but will probably require multiple applications, which isn’t that desirable; sometimes it’s best to replace deteriorated parts.

Note that not a single additive can fix massive cracks, no matter what the manufacturer’s say. The good news about our products is that they have integrity, and don’t promise any miracle-work.

Can Engine Oil Stop Leak Additive Be A Permanent Solution For Oil Leaking Problem?

Well, it depends on the seriousness of the situation. Many manufacturers will say that their engine oil anti-leak additive will provide a permanent solution, but we can’t agree with that statement. If this were true, everyone would just buy the additives and never replace the deteriorated rubber. Maybe it is possible to maintain protection over an extended period, but that’s simply isn’t affordable.

Final Thoughts

This review showed us that there’s a lot more than meets the eye when it comes to usability and the purpose of anti-leak additives. They come in different sizes, feature unique formulas and excel at something others don’t.

Your job is to work out critical decisions (regarding compatibility), and then move on to the application, prominent features, and other factors that make an additive excellent or bad. If you read this article carefully, you should be well equipped to make a solid judgment.

Also, if you do decide to buy the engine oil stop leak additive, make sure that you use the item safely and adequately: wear protective gloves, and use enough additives, but don’t overdo it. If everything goes as planned, your oil should stop leaking, and your budget, as well as your vehicle, will be very grateful for that.

4.4/5 - (11 votes)

Filed Under: Blog, Oil & Fluids

About John Smith

I have a Diploma in Vehicle Mechanics. I enjoy hearing from you, share your car problems, share ideas, and I will give you the best advises on how to solve your car problem.

Comments

  1. Marx Donzooya says

    May 6, 2019 at 3:09 pm

    I parked my Nissan Patrol for over 24 months & just recently woke her up. For the past two weeks, i have noticed some traces of oil on the floor where i parked the vehicle overnight. I have 128k on it. I am thinking of stop leak additives. Pls whats your take? Thanks.

    Reply
  2. swapna says

    May 16, 2019 at 8:02 pm

    Nice informative blog

    wht would happen if we combine lucas and blue devil, would it hurt the engine?

    Reply
    • John Smith says

      September 19, 2019 at 9:45 am

      all will be good

      Reply
  3. Elisabeth Southgate says

    September 13, 2019 at 6:20 pm

    Thank you for your information on oil stop leak additives. I found it helpful when you said that they have come a long and can stop most small leaks. My husband was saying the other day that he noticed that there is a small leak in our second car. Maybe we should consider using a oil stop leak additive to see if it will fix the issue.

    Reply
    • John Smith says

      September 19, 2019 at 9:42 am

      Definitely!

      Reply
  4. Tom Johnston says

    November 10, 2019 at 3:46 am

    Thanks so much for posting this valuable information John! I need your opinion regarding my 2008 Ford Escape 6cyl. with 93, 000 miles on it. My technician found a small leak coming from behind the harmonic balancer. It’s not enough to pool onto the ground but it is enough to burn off when it saturates the hot exhaust system causing an unpleasant odour in the vehicle as this occurs once vehicle is warmed up. I am hoping to use one of these products after each oil change and I am not sure after reading all your information, which of these products would be best to try? Thank in advance for any comments or further advice!

    Reply
  5. Thea LeGendre Cineus says

    February 29, 2020 at 2:09 am

    What anti oil leak product should I use for my 2006 Jeep grand Cherokee?

    Reply

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