The best oil stop leak is nothing short of a magic potion according to a lot of car owners, who have saved themselves hundreds of dollars in steep repair bills.

Oil leaks are pesky, and they can be dangerous.

Imagine a leak that saturates and subsequently weakens the timing belt. That’s a potential disaster in the waiting, and a very expensive repair bill to top it off.

That’s just one scenario though. If your old car or truck is leaking oil, chances are that it’s begun to percolate into other components that will continue to get degraded, the longer the leak is not plugged.

The problem with leaks though, is that it requires a trained eye by a mechanic to spot one, which translates into…(drumrolls)…. more money!

Some leaks, pinholes in particular, can be extremely difficult to spot. There may be no visible signs, like puddling or blue smoke. Yet, your car continues to guzzle oil.

Unless you have the budget to stretch, the best oil stop leak is the perfect solution.

It will fix the problem, add a few thousand miles to your car and save you from a huge bill.

But with hundreds of brands offering their oil stop leak products, it’s not easy to find the best one for your car.

This blog post will help you with just that.

Best Overall Stop Leak – Lucas Oil 10279

Last update on 2021-09-07 / Affiliate links / Images from Amazon Product Advertising API

Lucas Oil 10279 is one of the most popular oil stop leak additives in the market, and for good reason too.

It is a multipurpose formula that plugs leaks, and at the same time, reconditions old seals and valves. Think of it like a conditioner for old, battered engines that are guzzling oil.

It works by increasing oil pressure, which in turn helps to reduce oil consumption and also cuts down on engine noise.

If there are any tiny leaks that might have sprung, it addresses that as well.

A lot of oil stop leaks work by softening and expanding the seals in the engine. There’s a misconception that this causes the seals to wear prematurely.

But there are customers who have been using Lucas Oil 10279 for over a decade, and that’s testimony enough for its efficacy and safety. Be rest assured, this is completely safe for the gaskets and seals in your engine in the long run.

You can use this in automatic transmissions, hydrostat transmissions and hydraulic systems. Also, it is compatible with petroleum, semi-synthetic and full synthetic motor oils.

Using it is super easy. Depending on the condition of the engine, just add 10% of Lucas Oil to an engine with 90% fuel. Run your car normally for a couple of hundred miles and then allow it to rest. That’s it.

Irrespective of whether you are struggling with oil leaks, or are looking for preventive maintenance for your old engine, try out Lucas Oil 10279.

Best suited for: Plugging Pinhole leaks and preventing new leaks. Conditioning seals and valves in old vehicles.

Not suited for: Plugging larger leaks, which cannot be plugged by the reconditioned gaskets. Not compatible with diesel engines

Best for Stubborn Leaks – BlueDevil Oil Stop Leak

Last update on 2021-09-07 / Affiliate links / Images from Amazon Product Advertising API

The BlueDevil Oil Stop Leak is a top-rated oil stop leak that works with both, gasoline and diesel engines.

It is a universal product that can be used to plug leaks, even on the transmission and the power steering.

Unlike Lucas Oil 10279, which is better suited for plugging smaller leaks, BlueDevil is known to plug even large leaks in really old cars.

So, if you have a 25-year old car for example, which is in mint condition, but is starting to show telltale signs of oil leaks, then this might be an easy and cost-effective fix.

As long as it’s rubber seals and gaskets in the car, BlueDevil will soften and rejuvenate them. It does not matter what condition they are in (dried or shrunken or slightly cracked).

Using it is as easy as it gets. Just add 20-30 ml of BlueDevil to every liter of engine oil that you use and then drive around as normal. Whenever you get a chance, let the engine idle for a while. After a few hundred miles, you should notice that the leak has plugged.

In some cases, it might take more than one application. You do not need to change the oil after adding this, as it does not alter the composition of the oil or the fuel in the engine.

Best suited for: Plugging big and small leaks in engines, transmissions and power steering. Works with both gasoline and diesel engines.

Not suited for: This will only work with rubber seals and gaskets. It will not work with silicon.

Top Rated Brand – Bar’s Leaks OS-1

Last update on 2021-09-07 / Affiliate links / Images from Amazon Product Advertising API

Bar’s Leaks OS-1, is one of the oldest stop leak formulas in the market.

The brand has been around for over seventy years now and is a considered the best in-class for automotive and marine sealants.

This is their original and strongest formulation, that’s known to plug even stubborn leaks caused due to shrunken and hardened, seals and gaskets in heavy duty applications such as lawn equipment, tractors, RVs and ATVs.

When added to the engine oil, OS-1 releases synthetic polymers that form a secure seal around the gaskets. Over a period of days, it will soften the gaskets and revitalize them, thereby plugging any stubborn leaks.

That’s not all. When used as a preventive or maintenance additive, OS-1 helps improve engine performance by reducing oil consumption, slightly increasing oil pressure and scrubbing the internal parts clean. As a bonus, it keeps leaks in check.

The compatibility is excellent, as it can be used with a wide range of gasoline and diesel engines, including turbocharged, hybrid, racing engines and Eco Boost, and a variety of engine oils like high mileage, synthetics, blends and regular petroleum.

The number of applications required to fully plug leaks will vary depending on the extent of damage on the gaskets and seals. In most cases, a single application suffices.

Best suited for: Plugging severe leaks in cars, trucks and heavy duty agricultural, marine and high performance applications. Excellent choice for engine performance maintenance such as improving oil consumption, reducing engine noise, blue/white smoke from the tailpipe.

Not suited for: Well, this works for pretty much everything in the engine bay. Hard to go wrong with this.

Oil Stop Leak with no Petroleum Distillates – ATP AT-205

Last update on 2021-09-07 / Affiliate links / Images from Amazon Product Advertising API

The ATP AT-205 is a bestselling oil stop leak additive that contains plasticizers that help restore the flexibility of old, hardened rubber gaskets and seals.

In most cases, leaks are caused when gaskets and seals lose their flexibility due to plasticizers becoming lesser and lesser effective over a period of time. This rejuvenates the seals.

Bingo! No more leaks.

Even if your car is not leaking oil, but is an old car that might spring a leak sometime in the future, adding ATP AT-205 is a no-brainer way to keep the seals in pristine condition.

It can be added to any leaking engine, transmission, power steering, differential and hydraulic system. It is compatible with both conventional as well as synthetic oils like hydraulic oil, gear oil, ATF and power steering fluids.

The only possible leak that it cannot fix is one in the braking system. So do not add it to your braking system.

A lot of oil stop leak formulas contain petroleum distillates that can wreak havoc with the gaskets by over expanding them. ATP AT-205 is free of petroleum distillates and hence, is completely safe for the engine.

Using the ATP AT-205 is pretty simple. Just add it to the engine oil and allow it to circulate fully in the engine, which happens during operation. It takes up to five hours of operational time for this to happen.

Best suited for: Plugging leaks fast in engines, transmissions, power steering, differentials and hydraulic systems. No petroleum distillates and hence is completely safe for the seals and gaskets.

Not suited for: NA

Budget Priced Pick – NO LEAK 20401

Last update on 2021-09-07 / Affiliate links / Images from Amazon Product Advertising API

The No Leak 20401 is a pretty basic, oil leak stop additive that does a great job at plugging pinhole leaks and rear main seals.

A lot of oil leak stop formulas work fine for oil pan leaks or engine gaskets, but are ineffective at sealing the rear main seal. This one is highly recommended for it.

It’s also very effective at safely conditioning and rejuvenating, old, dried rubber seals. It works by softening these gaskets and expanding them safely, which should help improve the overall functioning of the engine.

The formula is compatible with both gasoline and diesel, and is well suited for cars used for every day driving and other similar applications. Apart from helping plug leaks, it also helps condition the engine and will help reduce excessive smoke from the tailpipe.

No Leak is one of the most economical choices in this list, which makes it a great pick if you are unsure whether an oil stop leak is going to work for you.

If this does not plug the leak even after 200 miles of driving, then the company (Gold Eagle) recommends that you contact a mechanic to get the vehicle inspected professionally.

Best suited for: Plugging pinhole leaks and primarily for rear main seals. Helps rejuvenate old, shrunken rubber seals.

Not suited for: Contains petroleum distillates. There are no complaints about this causing any damage so far. But a lot of car owners are not comfortable using additives with petroleum distillates.

Best Additive for Engine Maintenance – Bar’s Leaks – 1000 Engine Repair

Last update on 2021-09-07 / Affiliate links / Images from Amazon Product Advertising API

This is a multipurpose additive from Bar’s Leaks, one of the top brands in the industry.

Unlike the OS-1, which is their strongest formula for leaks, this one is more of a performance improvement additive for old, worn out engines.

It is a combination, dual action formula that contains a powerful blend of performance additives.

One part of it, called Formula A, contains high tech additives, friction modifiers and plasticizers for plugging leaks. The friction modifiers help reduce engine friction, which in turn should improve fuel consumption as well as overall engine performance.

The oil stabilizers in the other part of the formula, help to reduce dry starts as well as reduces overall engine temperature. It also contains viscosity improvers and seal conditioners that soften and expand all seals and gaskets.

In a nutshell, it’s an easy fix for a plethora of common engine niggles. You should notice a smoother running engine with no noise, no white smoke and a marked reduction in leakage.

A lot of customers have mentioned, that apart from no more oil leaks, they also noticed an immediate improvement in the drivability of the car. That’s because Engine repair rejuvenates worn cylinders, bearings, seals and rings.

It is compatible with a wide range of engine oils, that include gasoline, synthetics as well as high-mileage formulas. Moreover, it is completely safe for the engine and does not clog the oil filter or wear out the gaskets and rings prematurely. It also does not over expand the seals either, which is a common problem with such additives.

Best suited for: Stopping severe leaks and improving the performance in old engines. Helps condition seals, rings, bearings and worn cylinders.

Not suited for: High performance applications such as trucks and ATVs. The OS-1 formula is better suited for those.

Best Oil Stop Leak with a Money Back Guarantee – Hapco Products – Pro-Seal

Last update on 2021-09-07 / Affiliate links / Images from Amazon Product Advertising API

The Pro-Seal from Hapco products comes with a ‘Money back guarantee’. If this does not stop the oil leak in your vehicle engine, you get your money back. No questions asked.

So, how does that work?

Well, you can use the pro-seal with leaks in engines, transmissions, differentials, power steering and hydraulic systems. It is a non-clogging formula, that is free of petroleum distillates and does not wear out rubber seals prematurely.

So it’s completely safe for your engine.

Just add it to your engine oil, drive for about a hundred miles to allow the additive to circulate through the engine and idle the engine for a bit. That’s it. The powerful plasticizers in the formula will soften any hardened seals and make them more malleable.

This helps plugs even the stubbornest of leaks. That said, the formula is quite gentle and does not cause the seals to over expand. In other words, it will not block any parts of the engine where the oil must percolate.

If you have used it according to the instructions and it does not plug the leak, you can contact Hapco and claim a refund. To their credit, they have a very responsive customer support team and queries about the refund are answered promptly.

Best suited for: Stubborn leaks in the engine, transmission, differential, power steering and hydraulic system.

Not suited for: Bikes, lawn mowers, ATVs etc.

Alternative Oil Stop Leak – Liqui Moly 1005

Last update on 2021-09-07 / Affiliate links / Images from Amazon Product Advertising API

Liqui Moly has a range of engine oil additives that help solve common oil-related problems.

This is the Liqui Moly Oil leak stop 1005, a very effective oil stop additive that helps regenerate rubber and plastic engine seals.

If you are experiencing signs of oil leakage, such as the puddle under the car, or an oily coating on other components in the engine bay, this is one of the easiest ways to fix it.

It is a non-clogging, engine-safe formula that will soften and minimally expand shaft seals and valve stem seals. This usually suffices to plug severe oil leaks.

If you have an old vehicle, adding Liqui Moly will help maintain the integrity of the seals, and prevent expensive repairs down the road.

There are tons of customer reviews that speak about how effective Liqui Moly is, even in a single application. It’s only in rare cases that multiple applications are required.

Using it is as simple as adding it to the engine oil. After a run of about 500 miles, the additive will completely seal any leaks.

For those who are unaware, Liqui Moly is a very popular German Automotive brand that has won numerous awards. Their products are quite well received by customers all around the world.

Best suited for: Regenerating plastic and rubber engine seals. Plugging severe leaks.

Not suited for: Plugging leaks in motorcycles with wet clutches

Best Synthetic Formula Stop Leak – XADO ATOMEX

Last update on 2021-09-07 / Affiliate links / Images from Amazon Product Advertising API

If rigid, dried seals are triggering oil leaks in your vehicle’s engines, then XADO Atomex will fix it in no time.

This commercial-grade synthetic formula works like magic to help restore the elasticity of old seals and gaskets, thereby plugging leaks.

Also, it’s advertised as a more permanent fix, rather than a short term solution.

How many times have you used a stop oil sealant and gotten temporary reprieve, only to discover that the puddle reappears after a few months?

The XADO Atomex helps prevent the leaks from emerging again after a while, by maintaining the seals and gaskets in optimum working condition.

In the process, it also improves the performance of your engine, improving fuel consumption, reducing dry starts, engine noise and smoke from the tailpipe.

The formula is compatible with motor oils of all types

Best suited for: Plugging minor leaks, restoring the integrity of old, dried seals. Preventing leaks from recurring

Not suited for: Stubborn leaks in old cars.

FAQ

I have heard mixed reviews about these things. Does an oil stop leak really work?

In most cases, it does.

While there can be tons of causes for an oil leak, in a majority of situations, it’s caused by an old seal or rubber gasket that’s dried and lost its elasticity.

The best oil stop leak works to restore this elasticity by softening the seal. It contains a blend of polymers, also called plasticizers, which rejuvenates the seal, improving its functionality and expanding its lifespan.

This helps plug the leak, or at least minimizes it to a great extent. Subsequent applications may stop it completely.

In some cases, the seals are deteriorated beyond repair and even the strongest oil stop leak formulation cannot restore it back to life.

These are usually the customers who claim that these products do not work.

If you have tried oil additives to stop leaks, and it did not work even after two or three applications, then the seals might be worn out beyond repair and will need to be replaced.

Is this a band aid solution to a more pressing problem?

Like we mentioned earlier, that depends entirely on the condition that your vehicle is in currently.

In many situations, the best engine oil stop leak can stop the leak for a couple of years, or more.

You can then maintain the integrity of the leaks by using this to condition the seals and gaskets from time to time.

But in some situations, this can be a temporary fix. The question that you need to ask yourself is whether a temporary fix is the best solution at this point in time.

Sometimes, you cannot afford a $1000 bill right away. That’s fine. Spend $20-50 and use this as a band aid. If it buys you a few months, that’s not that bad, is it?

Can this damage my engine?

It does not.

If you are concerned about the seals and gaskets getting worn out prematurely, check out some of the best oil stop leaks without petroleum distillates, because distillates may cause some seals to over expand and wear out in a few months.

Oil stop leaks without distillates are completely safe for your engine.

How to select the best engine oil stop leak

Selecting Oil additives to stop leaks is a reasonably straight forward procedure, provided you have a fair idea about the condition of the seals and gaskets in the engine.

How bad are the seals in the engine?

Were you diligent about maintaining the seals? Have you used seal softeners in the past?

Were the seals ever conditioned? Are they dry and shrunken?

If yes, then you can opt for an oil leak additive that’s well suited for general maintenance, such as the Bar’s Leaks 1000 Engine repair, or the Lucas Oil 10279.

If the seals have never been conditioned, and the leak is severe, then opt for one of the commercial-grade formulas like the Bar’s Leaks OS-1 or the BlueDevil Oil Stop Leak.

Other than this, here are two very important factors to consider before you shop.

1. Petroleum Distillates: Some of the best engine oil stop leaks may contain petroleum distillates, which are long chain hydrocarbon solvents with a low surface tension. The advantage is that this allows these chemicals to percolate into the tiniest of crevices in the engine and scrub it clean. But, these are not too gentle on rubber seals and gaskets. They can cause the rubber seals to wear out and even dissolve in some time. The exact time might vary depending on the concentration of distillates in the formula. In some cases, it might happen months later. But if you have a car with silicon seals, this may not be a problem.
2. Plasticizers: Plasticizers are chemicals, mainly phthalates, that are added to an oil leak additive to help soften and increase the elasticity of seals and gaskets. These not only help plug leaks, but might actually increase the lifespan of the seals and gaskets in an engine. A formula with plasticizers should be a universal fit for a variety of applications, including

The intended application

Some best engine oil stop leaks are better suited for plugging pinhole leaks, while others are ideal for high performance, demanding applications such as trucks, ATVs and lawnmowers.

Choose one depending on the intended application.