Concentrated Rear Main Seal Repair (1040)

Concentrated Rear Main Seal Repair


  14 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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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 Concentrated 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 enchance 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

  14 Reviews
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 14 reviews
 by J. Elder - Altanta, GA

This product saved me a lot of money. It made a good car into a really nice car. I'm really sold on the Bar's Leaks Rear Main Seal repair, and I'll sure buy it again.

 by Timothy W. - Traverse City, MI

I don't normally do this, but I've found an AMERICAN company whose products actually work, and work WELL!!! So I had to write to thank you for your hard work and integrity in a world filled with automotive charlatans and snake-oil marketing.

Main seal leak stop saved my tractor. Oil leak stop saved my aging Subaru. Rislone keeps all my engines running clean and quiet, even with several hundred thousand miles! And Bar's Leaks has saved several radiators and heat exchangers. In a day and age where money does not go very far, your products help the average joe to keep a leg up, and repairs down, on a consistent basis!! I couldn't have kept three cars going through Northern Michigan's brutal seasons, while putting a kid through college without some help, and that came through in the form of several Bar's Products. Thank you folks, for your excellent products, and for keeping it simple, non-corporate, and integrity-based. Proud to be a fellow Michigander (Traverse City). Keep up the good work. You've got a devoted customer and free word-of-mouth advertising for life. -- Sincerely, Tim W.

 by F. H. - Orland Park

I just rebuilt my 1966 442 400 engine. I was apparently rusty on how to properly install the rear main seal (rope style) and it leaked almost from the get-go. I reluctantly put a quart of your product in my engine. I put over 100 miles on it and it still leaked. I was going to pull the engine and do it right at the end of the summer. Two days later I noticed there was no oil under the car when I pulled out of the garage. I couldn't believe it, the leak stopped. No oil anywhere under the car. Un-believeable.

 by D. B. - Fair Lawn

I have a 1985 Toyota Supra in mint condition; it has had an annoying small oil leak for over 10yrs now without finding a solution. I even tried engine oil stop leak from several companies without any luck. I saw your rear main seal conditioner and it was one that I never tried or heard of before so I tried it. WOW in less than 30 miles all the leaks stopped. Now with a total of 60 miles it still hasn'’t left any drops of oil on the garage floor. What a product. I will be adding it at every oil change from now on. Now my car is perfect once again. Thanks for coming up with such a GREAT product!

 by C. W. F. - Phoenix, AZ

I am now a big fan of your Rear Main Seal Repair. I have a 69 Firebird 400 conv. that I have practically owned since new. It is mostly all original with original drivetrain, interior and top. It has 105K miles and when I have taken it out of the garage it has left a trail of oil down the driveway. After using your product I was amazed that the leak stopped. I have used other products but nothing helped. I would be glad to endorse your product and if you are interested I can send you pictures of the car. Thanks for a great product.

 by J. E. - Burlington, NC

I have a 1966 Bronco that had a steady rear main leak. I changed the oil pan gasket in hopes this was the problem. I was going to change the rear main seal but it was a one piece type. This means the transmission has to come out to replace the rear main. I was very discouraged after performing this very large job only to find out I had the same problem. A buddy of mine recommended your product and I was a little hesitant of a product like this. To my surprise it worked after driving the vehicle for two day I had no leaks. I was so relieved that I wanted to take the time and thank you for such a great product. This saved me so much time and aggravation as I am a do it yourselfer.

 by T. V. - Las Cruces, CA

I am an amateur car collector and restorer (easy on the restoration). Recently I purchased a 1966 Ford Thunderbird, from the original owner. I drove it from Muncie IN. to New Mexico. After arriving home I started experiencing some problems with the car. Old cars have problems. The rear main seal was leaking. Before paying to have it replaced I used your Rear Main Seal restoration fluid. It worked perfectly! Then, I started getting water in the exhaust. Again, before paying for expensive repairs, I used your head gasket sealer. To my surprise it to worked perfectly! Your products have saved me hundreds of dollars in repairs. Just wanted to say thank you, and I will be recommending your products every chance I get.

 by R. F. C. - Denver, CO

I have a 1993 Allante Northstar, engine had a oil leak. Cadillac wanted $3,800.00 to fix it so I put a quart of Rear Main Seal Repair in the crank case I think it stop 99%. How long do you think this will last or should I try the same thing again, I also have a 1966 Impala with a leak around the rear main should I trust my luck, hoping to here from you, I have used your product since the 50’s keep up the good work an God bless all of you.

 by P. W. J. - Wrightstown, NJ

Hi my name is Paul I have a 1983 chaparal boat with a 120 hp io merc cruiser stern drive unit for power. Two weeks ago I noticed bad oil leak coming from the back of the motor. From where the leak was it looked like the oil pan was leaking, so my son and I went and put on a new oil pan gasket, the leak was still there. Not wanting to lose the whole boating season my father said I may want to try your Rear Main sealer. At this time I did not have $1800.00 dollars to repair it, so I tried your sealer. I ran the boat in my yard for about one half hour. I was disappointed as the leak was still there. I was losing a half a quart of oil in this short amount of time, after calling around again for repair prices I decided to try one more time. Being tired and mad I put the rpms from idle to 3000 and went into the house. after about forty minutes I went back out and I was shocked, I saw only a small amount in the drip pan. I could not believe what I saw! After checking the oil and measuring what was lost, I only lost a half of a cup of oil. I am very happy that repair in a bottle does work, Thank you for this product. I know that this is not a permanent fix but it looks like I will be able to use my boat for the rest of the summer season. I am hoping that my local parts store gets more in soon so I can have some on stand by. My son Ryan is a car repair tech and I told him to tell every one that this Rear Main sealer really works. Please do not stop making this product!

 by Joe D. - Tacoma, WA

I don't usually put additives in my vehicles, but I just recently purchased an old 1984 f250 with a 460 engine with a rear main seal leak. I heard these 460 engines always have trouble with the main seals leaking on them and I didn't want to do a major repair on this vehicle because all I need this truck for is to help me and my wife move. So I heard about the Bars rear main seal additive working good for some people and so I decided what the heck and put it in this old truck. Well I was very surprised how well this stopped over 95% of my leak and it worked within 2 days. All I have is just a little bit of wetness on the trans. bell housing and it doesn't drip at all like it used to. I am very pleased with this product. It saved me from having to do all that work. I would definitely buy this product again. Thank you Bars.

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