Best Engine Oil Stop Leak

My Guide to The Best Engine Oil Stop Leak

Every driver knows that an engine oil leak is one of the most annoying car problems. It’s right up there with a dying battery.

They can also happen very suddenly!

This is why you should check your motor oil levels regularly. Even a new car can develop a failed gasket. Checking the oil only takes about 3 minutes and it can help to save you a ton of headaches and money in the future.

So, what can you do once you find you have an oil leak, but you don’t have time or money to fix it right now?

An engine oil stop leak product can help. It will temporarily stop a minor oil leak until you can have the leak permanently repaired.

Which is the best engine oil stop leak?

Take a seat and I will show you the best engine oil stop leak for your car, so you stop leaving those ugly oil spots everywhere you go.

My Winner: ATP AT-205 Re-Seal

When it comes to stopping engine oil leaks, you want a product that will rejuvenate the rubber gaskets and seals. You don’t want to over-swell the seals so that they fall apart.

This is an immensely powerful compound that does NOT contain any petroleum distillates. Those help to prevent the breakdown of rubber seals and gaskets.

This is an 8-ounce bottle that is made to be added to 6 quarts of oil. It can also be used on other applications such as transmissions, power steering pumps, differentials, and other types of hydraulic systems.

ATP is the “re-sealer” that works quickly, often within a few hours.

ATP Re-seal can be used with all types of oil, including synthetic oils, gear oil, and other types of hydraulic fluids, such as power steering fluid.

Take caution though.

This should NEVER be used in the braking system, the cooling system, or the gas tank. There are other products for those if you need them (such as Bar’s Leak Cooling System Repair).


  • It’s fast acting and literally works within minutes. And in many cases, less than an hour
  • Its powerful formula really works (and for many people, it continues to work for years)
  • It’s very inexpensive


  • This is powerful stuff, so if you don’t use it according to the directions, you are going to cause yourself some serious problems.
  • A few users say that it made their leak worse
  • In some cases where this was used in other applications, some users say that it destroyed their system (power steering units especially seemed to develop problems)

When you consider that changing a rear main seal will cost you between $700 and $1500, and a can of ATP Re-seal less than $20, you should absolutely give this product a try.

It has proven itself to be a super effective way of stopping engine oil leaks.

Runner Up: SealLube Seal Expander Stop Leak

For those of you who are interested in stopping leaks in a variety of other applications, such as rack and pinion units, power steering pumps, and more, this product is top of the line.

SealLube is designed to restore the flexibility and elasticity of rubber seals and gaskets and not swell them to the point of no return!

This is a very wallet friendly option as well since one 8 ounce bottle will treat up to 8 quarts of oil or other fluid.

This works with diesel engines, transmissions, and all types of hydraulic units, including air conditioning units! That makes this one of the most versatile stop leak products on the market.


  •  It really works to recondition seals and stop leaks
  • You can use it on a wide range of applications
  • It’s very economical


  • Some users found the fix only temporary
  • Other users said the product didn’t work at all
  • In a few instances, it made the leak worse

If you use this product according to directions and the leak is not severe, you should be very happy with the results.

Remember that no stop leak will work on every seal in every instance. But this product is so flexible that there are zero reasons for you not to give it a spin.

Best Diesel Engine Oil Stop Leak: BlueDevil Oil Stop Leak

Not all oil stop leak products work with diesel motors. But BlueDevil has been around for decades and is well known for making quality products for diesel motors.

I like that the label spells it out so clearly, “Pour-n-go!” When it comes to stopping oil leaks in a diesel motor, that’s really all you need to do with BlueDevil.

It can be used with standard engines and other applications, but BlueDevil is made specifically for diesel motors.

I always lean towards using products that are designed for a specific purpose.

It only makes sense to take advantage of the investment a company made to make their product work in a certain application.


  •  In the majority of cases, this product stopped the oil leak within a few hours
  • It’s inexpensive when compared to repairs


  • Some users reported clogged lifters or oil pump screens
  • Others said the product worked temporarily or that it didn’t appear to do anything

In most cases though, BlueDevil worked remarkably well on diesel engine oil leaks, in some cases, for months.

How Do You Stop an Engine Oil Leak?

Oil leaks are very frustrating because they can come from more than one source. All engines will develop them at one time or another. But when you don’t have the time or the cash to repair the car, how do you stop an engine oil leak?

First, check the obvious. Oil filters can become lose or get cracked when they strike some road debris. The engine oil drain plug has a gasket that sometimes doesn’t get replaced, or a metal one can break.

The oil filler cap on the top of the motor sometimes gets lost or becomes loose. Look around the motor and see if you can determine the cause. If its not something simple, then it’s time for serious action.

Grab a can or bottle of engine oil stop leak! I talk about the best ones in my review above.

Read the directions carefully and use only as much as recommended. Give the product a little time to work. Depending on how severe the leak is or how much you drive, you should start seeing results in about 48 hours.

If the oil leak stop additive doesn’t substantially reduce the oil leak, you will need to bite the bullet and have the car repaired.

Can Oil Stop Leak Damage My Engine?

This would depend on your definition of “damage”.

While the oil leak stop additive won’t damage internal engine parts such as pistons, valves, crankshafts, etc, it does eventually cause damage to the rubber or silicone seals of the motor.

As a short-term solution, using an oil leak stop additive in combination with a heavier weight oil, synthetic oil, or high mileage oil is a good way of slowing down or stopping engine oil leaks.

Most oil stop leak additives cause the rubber seals inside the engine, such as the rear and front main seal, to swell. When the seal swells up, it reduces the amount of space that the oil can leak from.

Unfortunately, this swelling of the seals doesn’t stop. The longer or more often you add oil stop leak, the longer the seals will continue to grow until they quite literally start falling apart. This will make your leak worse than before, and in some cases, it can make the car undriveable.

For those of you who wish to try an oil stop leak additive, replace the oil with a heavier weight, synthetic, or high mileage oil. Then add the oil stop leak additive of your choice. If the oil leak is not substantially reduced, plan on having the car repaired in the next 3-5,000 miles.

How Long Does It Take For Stop Leak to Work?

This can vary from brand to brand. Most start working within hours. But the best way to get the full potential from an oil stop leak product is to drive the car.

Some say about 100 miles. That will get the product fully distributed and the engine heat will be applied long enough to allow it to do the job.

Keep in mind that the larger the leak, the longer it will take for the product to work. In some cases, it simply won’t work. If you are trying to seal a cork gasket, for example, an oil stop leak product will not work. Front main seals are also notoriously difficult to stop from leaking.

Most oil stop leak products work best when used exactly as directed on leaks that aren’t too severe. If you have a leak so severe that you are using a quart of oil every 50 or 100 miles, no amount of stop leak is going to help.

But for those minor leaks in a valve cover gasket or rubber oil pan gasket, where you are adding a quart of oil every 1,000-1,500 miles, this is the perfect solution.

Always read the directions on the product you have chosen. Not all oil stop leak additives work the same. Some cannot be used on diesel motors while others do not work with synthetic oils. Use as directed and you should have excellent results.

How Much Oil Stop Leak should I use?

This will depend on the manufacturer’s directions.

Many products are designed to replace approximately 20% of the oil capacity of the motor. For example, if your engine holds 4 quarts of oil, then 1 quart of oil stop leak should be added.

Some products are a concentrate. So you will add less than the example above. It’s important to take a few minutes to read all the instructions on the bottle so that you don’t use too much or too little.

Engine oil stop leak is not one of those “more is better” products. Adding more than the container directs you to add will NOT make the leak stop faster or take care of a larger leak.

If the recommended amount does not substantially stop the leak, you will need to repair the damage.

Will Heavier Weight Oil Stop Leaks?

Yes, heavier weight oil will stop oil leaks up to a certain point.

As your car’s motor warms up, the oil becomes hot and thins out. This allows the oil to leak through failed gaskets and seals.

If you use a thicker or heavier weight oil, or synthetic oil, it can prevent the oil from finding its way through very small tears or breaks in the seals or gaskets. But even that won’t stop all the leaks.

The only true way of stopping an oil leak is to repair the problem. Whether it’s a leaking valve cover gasket, a failed rear main seal, or an oil pan gasket, you’ll need to get it fixed.

Some oil leak repairs aren’t expensive and are fairly easy (an oil drain plug gasket, for example). Other parts can be terribly expensive such as the front or rear main crank seal.

If you are simply buying yourself some time until you can have the vehicle repaired, changing your lighter weight oil for synthetic oil or a heavier weight oil will help.

The Winner

I’ve tried many stop leak products in my lifetime. I have to say that ATP Re-seal is the absolute best engine oil stop leak product that I have ever used.

I’ve mentioned before that I own a rather old SUV. After 150K, it developed an oil leak from the rear of the oil pan. It couldn’t have happened at a more inopportune time. I needed the vehicle for a few more months before I could get around to having it repaired.

ATP Re-seal worked like a charm. I added nearly the entire bottle to the engine oil when I left the house for the day’s errands. I checked underneath my ride about lunch and there was NO leak!

If you have an engine oil leak and you can’t or don’t want to have it repaired right away, I highly recommend using ATP Re-seal. Chances are that you will be trading in that car before this product stops working.

I’m betting that even the most hard-core skeptic will find that this product exceeds expectations.

Don’t forget to read the directions carefully and follow them EXACTLY.

For less than $20- what do you have to lose?

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