Fixing a leaky engine sounds like a major automotive repair that will cost you an arm and a leg. But in some cases, a handy oil additive known as "oil stop leak" can come to the rescue and restore your engine's structural integrity without needing to take it apart. Often, this oil additive can also stop future leaks from occurring by reinforcing existing seals and gaskets effortlessly.

Of course, not just any old bottle of oil stop leak will do the job when it comes time to take care of your car or truck’s valuable engine. By all means, you should find the best oil stop leak option based upon your motor type as well as the liquid’s unit price. These reviews of the top 7 best oil stop leak additives will highlight these important qualities and more, so I highly recommend reading them before stopping into your local auto parts store.


Preview

Product

Weight

Engine Compatibility

Check Price

Lucas Oil 10278 Engine Oil Stop Leak

Lucas Oil 10278

32 ounces

petroleum, semi-synthetic, full synthetic

ATP AT-205 Re-Seal Stops Leaks, 8 Ounce...

ATP AT-205

8 ounces

Gasoline and diesel engines, as well as transmission, power steering, differential, and hydraulic systems

STP 19065 Car Tire Inflator and Sealant - For...

STP 15604B

15 ounces

Most SUVs and light trucks

Liqui Moly 20132 Radiator Stop Leak, 0.25 l,...

Liqui Moly 20132

8.45 ounces

Aluminum or plastic radiators

Bar's Leaks 1040 Grey Pack of 1 Concentrated...

Bar's Leaks 1040

16.9 ounces

N/A

BlueDevil Oil Stop Leak

BlueDevil 49499

8 ounces

Gasoline and diesel engines

TriboTEX Nano Oil Additive Car Engine...

TriboTEX Nano

1.6 ounces

Universal


What Causes an Engine to Leak?

Oil can leak into a car or truck's engine for a number of reasons, though most common leaks are caused by damage or degradation of the engine's gaskets. These seals can wear down over time, allowing oil to directly contact the engine and produce the blue-ish tailpipe smoke that often signals an oil leak. Often, these kinds of leaks can be resolved with some oil stop leak liquid.

Oil may also begin to leak into the engine if the oil drain plug or the timing cover seal is damaged. These are problems that oil stop leak liquid can’t fix on their own, so those who use this oil additive and find it ineffective should consider having a mechanic check their vehicle for these leak-related issues.


Types of Engine Oil Stop Leaks

Absorbent Formulas

As its name suggests, this type of oil stop leaks absorbs into your engine's architecture to form fresh seals at degradation points. This type of liquid is currently the most common on the market due to its high reliability.

Particle-Clogging Formulas

This type of oil stop leaks was originally formatted only to plug up holes in engines, rather than create new seals. As such, it is less reliable and won’t last as long as more modern oil stop leaks formulations. Still, this liquid is widely available and may be used in a pinch.

Combination

This type of oil stop leaks gives you the best of both worlds as it simultaneously clogs up troublesome engine leaks and makes fresh seals for more long-term dependability. Many popular oil stop leak brands use a combination formula to meet every mechanics needs without needing separate products.


Choosing Oil Additives to Stop Leaks

Type of Oil Additive/Stop Leak

As you shop around, you’ll quickly find that there are lots of different categories for oil stop leaks based upon their precise formulation. For example, many auto goods stores carry oil stop leak types categorized as a "complete engine treatment," "heavy-duty oil stabilizer," and "high mileage oil stabilizer," for example. Be sure to speak with your mechanic to determine which type is appropriate for your situation.

Efficiency

Naturally, you’ll want to find an oil stop leak liquid that is highly effective and maintains its productivity for a decent amount of time after you use it. You won’t find this measurement on the bottle, though; your best bet for figuring out oil stop leaks efficiency is by reading through other users’ qualitative reviews of the product in question.

Activation

This metric is included with some types of oil stop leaks to communicate how long or under what circumstances the liquid can take full effect. Sometimes, an oil stop leak liquid will activate in just a few hours, while others require a certain number of miles to be driven before the liquid is successfully spread throughout the engine.

Engine Compatibility

Don’t forget – not every type of oil stop leak is compatible with all engines or fuel systems. As such, you should always check a prospective liquid’s listing before using it to avoid costly damage to your vehicle. When in doubt in this domain, don’t be afraid to ask a professional mechanic like me for help differentiating each oil stop leak type.

Plasticizers

These are a chemical component of some types of oil stop leak that allow the plastic components of your engine’s existing seals to “regrow" and return to their formally productive state. The plasticizer used in each brand's oil stop leak liquid is a little different, though, leading to varying levels of effectiveness under different circumstances.

Petroleum Distillates

Though costly at times, this chemical component of high-end oil stop leak liquids can make a major difference for your engine if you believe that a damaged gasket is to blame for your oil leaks. Be aware, though, that these distillates are known to cause more engine wear over time, making them a risk for prospective users who want to maintain their engine’s health long-term.


7 Best Oil Stop Leaks Reviewed

1. Lucas Oil 10278

Our Top Pick!

Weight

32 ounces

Cleans Sludge?

No

Chemical Composition

100% petroleum

Activation Speed

N/A

Engine Compatibility

petroleum, semi-synthetic, full synthetic

First off, I have to give my top pick for best oil stop leaks liquid to the white bottle we keep around our auto shop - Lucas Oil 10278. I’ve always enjoyed the fact this bottle’s labeling says “it works!” because it really does, regardless of whether you use petroleum, semi-synthetic, or full synthetic motor oil in your vehicle. This liquid is chemically composed from 100% petroleum too, so you know that it is free of harmful solvents that can cause corrosion while they work through your engine’s system.

As a mechanic, I’ve also always appreciated Lucas’ attention to detail when it comes to marketing this product. Indeed, it comes in several different sizes, making it easy for a mechanic like me to buy and bulk to save money on multiple engine sealing jobs. The nozzle on this additive’s bottle is also tapered, so you won’t need to get out a funnel or worry about splashing this hazardous solution around at all.

Pros

  • Wide-ranging compatibility with all major oil types
  • Tapered bottle nozzle makes it easy to pour in
  • Comes in multiple sizes
  • Can reduce engine noise and oil consumption

Cons

  • Lacks a listed activation speed
  • Does not clog larger leaks

2. ATP AT-205

Best Rated Option

Weight

8 ounces

Cleans Sludge?

No

Chemical Composition

Plasticizers, no petroleum distillates

Activation Speed

Up to 5 hours

Engine Compatibility

Gasoline and diesel engines, as well as transmission, power steering, differential, and hydraulic systems

I’ll admit, I was a bit surprised to learn that ATP AT-205 was the best rated option on today’s oil stop leak market. But as it turns out, current and former users of this oil additive are raving about all of its productive qualities. Often, these users mentioned the fact that this liquid’s chemical composition lacks petroleum distillates, which in turn makes it fully compatible with a wide number of oil-related vehicle systems.

To that end, ATP AT-205 doesn't cause any adverse reactions when mixed with conventional and synthetic oils, ATF, gear oil, power steering fluids, or hydraulic oil. So, you could actually buy a couple 8 oz. bottles of this stuff and keep it around in case your transmission, power steering, differential, or hydraulic system springs a leak. You’ll be able to resolve that leak in a jiffy, too, because this liquid activates and begins to seal up leaks after only 5 hours of use.

Pros

  • Fairly quick activation speed
  • Can be used in gas and diesel engines, as well as many other oil-based systems
  • Doesn’t contain petroleum distillates that are known to cause corrosion
  • 1 bottle is adequate for many common car engines

Cons

  • Not as effective in trucks
  • Very thin and not as viscous

3. STP 15604B

Top High Mileage Option

Weight

15 ounces

Cleans Sludge?

No

Chemical Composition

Zinc anti-wear agent “ZDDP”

Activation Speed

N/A

Engine Compatibility

Most SUVs and light trucks

I’ve known this for a while, but I want you to know that STP 15604B is a clear choice for top high mileage option on today’s automotive repair market. This is because this liquid’s chemical composition contains one additive, known as "ZDDP," that other treatment formula's lack.

This additive contains zinc, which, in practice, can reduce friction that leads to leaks in the first place. Of course, you can also count on this high viscosity oil leak stop liquid to repair seals while it is being processed, thus ensuring that your SUV or light truck is as safe and noise-free as can be.

I must say, STP 15604B is also particularly cheap per bottle at only a few dollars for a 15-ounce container. That’s good, though, because STP expects you to use more of this treatment after every oil change, rather than just when a leak appears. If you follow these recommendations, I do believe that it will help reduce your vehicle’s oil consumption overall.

Pros

  • Very cheap per bottle
  • Utilizes unique zinc anti-wear agent
  • Can reduce oil consumption if used regularly
  • High viscosity formula seals up leaks swiftly

Cons

  • Designed to be used with each oil change
  • Not effective in non-automotive uses

4. Liqui Moly 20132

Best For Radiators

Weight

8.45 ounces

Cleans Sludge?

No

Chemical Composition

N/A

Activation Speed

10 minutes

Engine Compatibility

Aluminum or plastic radiators

As you may already know, not all oil leak stop liquids are designed for all uses or even for use in the main engine at all. That’s why I want to recognize the best option for a radiator leak, Liqui Moly 20132. Though I am not precisely sure of this option’s chemical composition, I can say with confidence that Liqui Moly has done something special with its formula. That's because it activates in only 10 minutes and can seal up most leaks in either an aluminum or plastic radiator.

Both before and after using Liqui Moly 20132, you can forget about flushing because this formula is entirely safe to apply directly to existing cooling fluid. Also, much to my surprise, Liqui Moly 20132 can secure the internal combustion chamber against coolant admission, which most other multipurpose oil leak stop liquids simply cannot claim. Liqui Moly 20132 is made in Germany, as well, so you can count on its manufacturing team to support any and all return policies it offers if you are not satisfied with its quality.

Pros

  • High-quality formula made in Germany
  • Easy application and quick activation
  • Works in most common radiators
  • Doesn’t require flushing

Cons

  • Lacks listed chemical composition
  • May not work on hairline cracks

5. Bar's Leaks 1040

Best For Sealing Rear Main Leaks

Weight

16.9 ounces

Cleans Sludge?

No

Chemical Composition

Plasticizers

Activation Speed

100 miles or 2 days of driving

Engine Compatibility

N/A

Rear main leaks are all too common these days, so I want to make a recommendation for the best option for sealing rear main leaks as well. Specifically, I want you to consider this hefty bottle of Bar's Leaks 1040 next time you discover a rear main leak in your vehicle. At 16.9 ounces per bottle, you get a lot of bang for your buck with this one. In fact, you could even seal up a timing cover or cam seal with this single bottle without wasting a drop.

I'll be the first to admit that Bar's Leaks 1040 activates pretty slowly. It may take as many as 100 miles of driving or 2 days of use to allow it to take full effect. This is a direct result of the plasticizers used in this liquid formula, which will enable it to form a polymeric film that will last for thousands of miles of wear thereafter. This liquid cannot seal major leaks, though, so be sure to make use of Bar's Leaks 1040 before too much of your engine's seal has degraded.

Pros

  • Effectively fixes rear main seals by building a polymeric film
  • Also works on timing covers and cam seals
  • Large volume per bottle

Cons

  • Rather long activation time
  • May only partially seal larger leaks
  • Does not list their product’s compatibility

6. BlueDevil 49499

Compatible For Diesel Engines

Weight

8 ounces

Cleans Sludge?

No

Chemical Composition

Glycol, non-clogging

Activation Speed

N/A

Engine Compatibility

Gasoline and diesel engines

Truck owners need an oil leak stop option that is fully compatible with their diesel engines. For this specific purpose, I recommend purchasing a bottle of BlueDevil 49499. With only 8 ounces of this additive, you’ll be able to efficiently repair your truck’s engine seals without putting the very same system at risk for corrosion. This is because BlueDevil 49499 utilizes a unique glycol formula that prevents clogging entirely, even several months after it has been added to the motor oil.

That being said, I do want you to know that BlueDevil 49499 can be a bit expensive per bottle, not to mention a little harder to find at your average auto parts store. It also tends to be a bit waterier than most first-time users expect, which can cause them to distrust its results in diesel engines. But even so, you can rest assured knowing that numerous truck specialists keep BlueDevil 49499 in their shop and will whip it out whenever their customers need a quick oil leak fix.

Pros

  • Fully compatible with diesel engines
  • Non-clogging glycol formula
  • Easy to use and doesn’t need to be re-applied

Cons

  • A bit expensive per bottle
  • A bit watery

7. TriboTEX Nano

Top Of The Range

Weight

1.6 ounces

Cleans Sludge?

No

Chemical Composition

Synthetic nanoparticles

Activation Speed

500 miles

Engine Compatibility

“Universal”

Finally, let’s look at one of the oil stop leak options that many folks consider to be “top of the range” -  TriboTEX Nano. While I haven’t used this liquid in my own shop before, my fellow mechanics have vouched for its quality. Based upon their description, I’d call TriboTEX Nano pretty ground-breaking when it comes to engine maintenance. That's because, with only ~1.6 ounces of this liquid, you can repair and protect your engine against future links.

This is because TriboTEX Nano uses a unique formula of synthetic nanoparticles that immediately stick to all internal surfaces. It then begins to repair existing seals and bearings found therein before covering the finished work with a diamond-like carbon coating. This process works in almost all kinds of automotive engines as well, including some motorcycles. Just be sure to plan ahead, though, because TriboTEX Nano takes a whopping 500 miles to set correctly after being applied.

Pros

  • Made in the USA
  • Creates diamond-like carbon coating to stop leaks
  • Universal compatibility
  • Works on warm or cold engines

Cons

  • Very expensive per unit
  • Activates slowly over 500 miles

How to Use Oil Leak Stopping Fluid

When it comes to applying an oil stop leak, you're in for a reasonably straightforward process that won't require a mechanic's help at all. In fact, so long as you've already identified the source of your engine's oil leak, you'll be able to pop open the oil cap and just pour in the liquid according to the instructions on its bottle. Should you need it, this helpful video will take you through the process of finding the source of your vehicle’s leak as well as the process of pouring in this product.


Why Is It Good to Stop Oil Leaks?

First off, oil leaks are always a costly proposition. Not only does it cost a lot to keep refilling your engine's oil regularly, but it can also result in other motor components becoming damages due to infiltration by the leaking oil. As a result, you could be looking at several costly repairs if you don’t plug up an oil leak in short order.

Along the same lines, stopping a leak quickly means that you'll be able to keep your vehicle's engine in better shape for longer. This is especially true when it comes to the engine's seals or gaskets, which some oil stop leaks formulas can rebuild and protect against future leaks.


People Also Ask (FAQs)

Will oil stop leak harm my engine?

Not necessarily, no. However, an oil stop leak is known to soften seals that were not hardened or damaged, so this can change how long they can last compared to the other recently repaired internal engine seals.

What is the best oil additive to stop leaks?

There are several oil additives that my fellow mechanics and I swear by today. In fact, we always keep a bottle or two of Lucas Oil 10278 and ATP AT-205 just in case a customer comes in needing a quick oil leak fix.

What should I do if leaking continues?

Often, this means that your oil leak is being caused by something more serious than a weak seal or gasket. Accordingly, you should make an appointment with your preferred mechanic as soon as possible so that they can diagnose the problem more effectively.

Is it safe to drive with an oil leak?

In most cases, yes. However, drivers with a known oil leak should not drive in this state for long due to the risk of running out of motor oil entirely. Ideally, you should only drive with an oil leak if you are going to fetch oil leak stop liquid or to visit your mechanic.

What are the top brands of oil stop leak?

There are numerous popular oil stop leak brands out there today, many of which are well-known for their oil-related products in general. For example, you can usually trust Lucas, ATP, BlueDevil, and STP brand oil stop leak liquids.

What are the possible side effects of using it?

Most oil stop leak liquids don’t list specific side effects. That being said, your preferred mechanic can provide you more insights into whether a particular brand’s formulation is more likely to help or hurt your engine’s long-term health.


Conclusion

At the start of the day, I bet you didn’t even know that there were this many different types of oil stop leak liquids or even how this fantastic product worked in the first place. Well, now you know just about everything a regular vehicle owner needs to know about owning and using oil stop leak liquid, allowing you to use it on your own car or truck as soon as today.

If you’re in a hurry, though, and don't want to shop around, be sure to look for a bottle of Lucas Oil 10278 when you get to the automotive store. This liquid is fully compatible with all petroleum, semi-synthetic, and full synthetic motor oils, thus decreasing the chance of corrosion down the line. It also comes in multiple volume sizes, so you can always keep a bottle to spare if you expect the need to use more oil stop leaks in the future.

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