Heavy Duty Rear Main Seal Repair (1040)

Heavy Duty Rear Main Seal Repair


  32 Reviews

The engine oil repair formula that made us the #1 brand for all oil leaks stemming from the rear main seal, timing cover, cam seal and anywhere else you’ll find troublesome oil leaks! Millions of bottles sold, and so easy anyone can do it – no technical expertise required. Safe, effective and affordable, and backed by Bar’s Leaks’ reputation as a premium chemical repair company since 1947. We specialize in keeping your car on the road and away from unnecessary expensive repair bills. If you are dealing with an engine oil leak, you’re in the right place.


Add entire bottle of Rear Main Seal Repair to engine crankcase (where you normally add oil) at or between oil changes. Do not overfill. Most leaks will stop within 100 miles or 2 days of driving. To prevent future leaks and for outstanding preventive maintenance, install Rear Main Seal Repair every 5,000 miles or with every oil change.

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  • Heavy Duty Formula
  • Stops All Oil Leaks
  • Seals Timing Cover, Cam Seal, Rear Main and Other Hard-to-Stop Oil Leaks

Bar’s Leaks is the leader that specializes in chemical solutions for rear main seal leaks and other automotive issues. Our products are effective and affordable. And they’re easy to use, too. If you know how to pop the hood on your car, you can install our rear oil seal solution. We design our products for ease of use, because a good solution isn’t very helpful to everyday drivers if they can’t use it. At Bar’s Leaks, we do everything we can to get you back on the road in good condition just as quickly as possible, by offering rear main seal leak products and much more.

Most rear main seal leaks are caused by a combination of normal wear in the crankshaft and seal combined with the drying, hardening and shrinking of the main seal. Bar’s Leaks Heavy Duty Rear Main Seal Repair restores the seal to like-new condition, and also contains additives to stop leaks in severely worn seals and crankshafts. Not to mention, it works with ALL gasoline and diesel engines using conventional, high mileage and synthetic oil. We’ve gone to great lengths to ensure that our rear oil seal solution is working for you in all possible ways. You can count on us for a rear main seal leak that takes care of your problems and helps prevent future leaking.

You can trust that our products are the fastest, safest way to get your show back on the road — we’ve been proving that since 1947.


For nearly 70 years, the team at Bar’s Leaks has been working to serve everyday drivers just like you with affordable, easy-to-use, effective chemical repair solutions for a range of automotive problems. These solutions include our oil stop leak products, as well as solutions for cooling systems, head gaskets, power steering, transmissions and much more. While you’ll find plenty of options when searching for a rear oil seal product, you won’t find the same level of effectiveness you’ll get with Bar’s Leaks.

Our products are developed and manufactured in the United States, just an hour outside of Detroit. Our top-flight chemical engineers are always searching for ways to enhance our existing products and to develop new products in response to new automotive innovations and technologies. When you want the best rear main seal leak solution available, look no further than the track record of success at Bar’s Leaks.

Grab your rear oil seal solution today.

Customer Reviews

  32 Reviews
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 32 reviews
 by Robert Y.
Competitor product didn't work, yours did

Just wanted to thank you. My museum quality 73 Chevy Luv 355 has had a rear main seal leak for a long time. Tried the competition and it slowed it down. Last oil change I tried your product. It worked fantastic! My baby is now completely oil leak free! I'm now a fan for life and will be spreading the word. Thanks again!

 by David J.
You saved me a ton of money, thank you!

I was very pleased using your Rear Main Seal Repair. I was looks at a $4000-5000 engine repair to my 1993 Cadillac Allante. To repair seals on my car the entire engine must be removed from the car! I had tried another brand of so called engine repair that did nothing as far as seal repairs. I ordered two (2) different Bar's Leaks products before my last oil change and asked the mechanic to use instead of oil. I was very pleased after about a week that the leak was almost repaired, I ordered and added an additional bottle of Rear Main Seal Repair and as of today I have NO leaks. Thank you!

 by Marc G.
Definite improvement

I have a 2005 LaCrosse where I used Bar's Leaks Heavy Duty Rear Main Seal Repair (1040). Definite improvement, reduced oil leak significantly.

 by Rick B.
Very impressed

Recently on my 80k original mile 2008 4.0 SOHC Ford Ranger I went to change the oil and couldn't find the Motorcraft 5w30 synthetic blend oil that I have been using for the 4 years that I have owned it. My entire drivetrain has been dry & completely free of leaks. I ended up buying Mobil 1 full synthetic 5w30 oil. It has been in the engine for 2000 miles now and I noticed a leak which I am 100% certain was at the Rear Main Seal. I strongly suspect the Mobil 1 oil caused this leak in an otherwise completely dry, leak-free engine. Yesterday I drained the Mobil 1 and put my Motorcraft oil back in along with your HD (16.9oz) Rear Main Seal in, I then drove 100 miles as per the instructions on the bottle. I varied my speeds from 25 mph to 70 mph and when I got back home I slid a piece of cardboard under the engine there wasn't a single drop of oil to leak onto it! I have used your products since 1973 with great success in cooling systems and am very impressed with the performance now of your Rear Main Seal worked. So thanks for that!

 by Jacqueline W.
Fixed our problem, would use again

Rear Main Seal Repair is what we used. It did fix our problem and I will definitely consider the product again. Thank you! 

 by John G.
Cheaper than mechanic

Used Bar's Rear Main Seal Repair for my 2000 Jeep Grand Cherokee, which was leaking for awhile. I used it once with a fresh oil change which slowed the leak down some. After 3000 miles I changed oil and added another bottle of Bar's Leaks Rear Main Seal and drove it for another 1000 or so miles and the leak was gone. I've put on approximately 20000 miles since then without the leak reappearing. Was cheaper than replacing the rear main seal.

 by Charles B.
Stopped the leak for good

Heavy Duty Rear Main Seal Repair 1040 was the product I used.  

There was a small oil leak, and the product seemed to stop the leak for a while in my ‘08 Impala. Later I had valve cover gaskets replaced that stopped the leak for good. I'm not sure I had to do that, but I figured why not.

 by Beau D.
Did the trick for my Jeep with 250K miles!

I’ve used Bar’s Leaks products for over 40 years. My father owned an auto parts store, and we sold Bar’s Leaks. Back then people relied on the radiator sealer religiously. I recently used the Heavy Duty Rear Main Seal (#1040) on a slow drip on my 2006 Jeep and it did the trick. The Jeep has 250K miles and hope to get that much more out of it.

 by Steven S.
Worked like a charm, saved me huge money

My name is Steven and I had a 2000 Toyota Tundra with about 300,000 miles on it. The rear main seal was leaking, and I was quoted 500 for parts and labor. I ended up buying Bar's Leaks Heavy Duty Rear Main Seal Repair. And let me tell you; it worked like a charm. No more leak nothing saved me huge money.

 by Semitrucking
Worked great

I used the rear main seal repair part number 1040 in my 1953 Ford 801 PowerMaster tractor and it worked great. Thank you!

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