Bar's Leaks Rear Main Seal Repair, 16.9 oz

I'll start by saying this product goes against everything I believe or have been taught about internal combustion engines, the two most prevailing thoughts before ordering this were:#1: Only oil goes in the crankcase, nothing else#2: Snake oil does not work, especially for a long term solution, fix the real problem instead of throwing money and additives at the problem that ultimately may do more harm than goodI have a small block ford engine that has a notorious rear main seal leak, drips engine oil right at the transmission bell housing. Started small and got worse. This is a well documented problem, and the transmission must be pulled to replace the seal. I have heard many stories of people who have replaced the seal, only to have the brand new one leak too, people have tried crankshaft sleeves to make the fit tighter, and with mixed results. I did not want to go down this road unless I had no other option.I did a little research on this product, and the reviews are mixed. I have not heard any horror stories worse than "it didn't help and I wasted my money on this product", and from what I understand it works completely differently than the "leak stop" additives you would use for a head gasket, coolant leak, air conditioning system leak, or tire leak. All the latter leak stop additives are adhesive products which are glues and materials designed to fill cracks/voids and cure on contact with air. This product works differently. This product is not an adhesive of any kind and does not leave any residue. It is basically a solvent that attacks rubber and causes it to swell. This makes the seals fit a little tighter if the only problem is a seal is a little old or dried out. If the seal is cracked, deformed, or a synthetic material that the active ingredient in this product doesn't react with (its designed for rubber, not corks, silicones, etc), this product will most likely not help.I dumped this in the oil reservoir. It was already a little low from the leak, so the excess oil in the crankcase was not an issue. Ran the engine for about 30 mins and no change, still same dripping while running. I drove the vehicle every day approx 30 miles. After a week, the leak was barely noticable, just the bottom of the transmission housing felt a little oily, but no puddle/stains in the driveway. After 2-3 weeks, the leak was gone. And I mean gone, not a drop. I was impressed how well this worked on this problem and thought it fixed it permanently. Then about 4000mi later, I did an oil change. For the first few hundred miles after that, no leaks, then after about 1k miles, I noticed the leak started to return. I immediately picked up another bottle of this stuff and dumped it in, about 1 week later, the leak was gone. I now don't even mess around anymore and just add a bottle of this stuff to every oil change, and it is under control, its a small price to pay (even for life of vehicle) to not have to deal with the rear main seal. For me, this product makes a night and day difference, I have been using it for approx 30k miles, but depending on the root cause of your leak, your mileage may vary.

Used Valvoline Restore n Protect and it caused the rear main seal to leak in my wifes Jeep. Been using AT205 every oil change but it only reduces the leak.I used this Bar's Leaks on the last oil change a few weeks ago and within a week it has stopped leaking.I'm very happy with the results as I do not want to put this Jeep in the shop. It's not only the cost of $1,500 to have the seal changed but the inconvenience of it. I know sooner or later it will have to be done but I'll cross that bridge when I HAVE to

This works well. Kept my engine from burning oil...Thank you!

I gave this product a try and could not believe its results. I read some reviews and that convinced me to try it out on my V6 Cherokee. After a few days, the oil leaking on the rear seal start to disappear. it is a very small leak with no dripping on the floor. but the leak was very noticeable as it used to smell oil when driving the car. The smell is almost gone after a few days driving the car. not sure how long this will last... I will continue to add one on every oil change and hopefully it will keep the small leak under control.

Didn't seem to work well on 2011 audi q5 with rear mainseal leak. Looses oil faster now then before the product. Ive used it on my old suburbans, seems to do well there though. Imagine its a different type of damage. Q5's are notorious for having weak mainseals.

Great value and quality

thought i would give it a try, figured it couldn't make anything worse. it did not work. seems like a waste of money.

I own a 20 year old SUV that I simply love to drive. It runs great, looks great and it's been paid off for many years now. It just clocked 200k miles and the rear main seal started leaking. While I don't mind putting money into it, I tried this product first.Well, I am pleasantly surprised. Many reviews here stated the vehicle needs to be driven a few hundred miles before results are apparent. I drove my SUV 12 miles after adding the stop leak and I'll be damned if the leak hasn't stopped.I will keep an eye on the condition but for now, the stuff works. Will follow up if the leak returns.I've run up about 400 miles and no leaks so far. 300 to 400 miles and the leak has sealed up the problem. That seems about the average working milage. Good product, just be patient....