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 good I 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.

I just wanted to share a quick note about this product I used it about a year ago and since then really saved me a lot of trouble (and money!). My old truck, a trusty 2004 model, had developed quite an oil leak, losing about 1 to 1.5 quarts every single month. I was seriously considering getting rid of it because the thought of paying for expensive mechanic repairs just wasn't worth it for a vehicle of that age. It felt like a losing battle. But then I tried this product, and honestly, it's been a game-changer! It's been a full year since I started using it, and my truck is still running strong. I genuinely don't notice any oil loss anymore, which is fantastic. It does take some time to notices the product stars working but at the end of couple weeks you may start seeing that stars working. I've been adding it every other oil change. I'm not sure if that's overkill, but I'm just so thrilled to still have my truck and avoid those costly repairs. It's fantastic to have it back on the road without constantly worrying about the oil levels. Just wanted to pass along my positive experience!

Seems to work good, not perfect but definitely slowed down the leak quite a bit. I was getting a lot of drips from the rear main before, but now it's almost stopped, but not completely. I get a few drops here and there is all. Nothing major. So I'd say this project does it's job pretty good.

Bought the first bottle and it slowed the leak to a drip. Bought another bottle and added it at the oil change and it stopped completely. It was a bad rear main seal leak in a 2017 Subaru forrester. I will probably add again at the next oil change until spring gets here and I can change the seal.

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.

Leak stopped immediately. Was a small main seal leak but this stuff worked

Do not use this stuff, you will ruin your engine. Just get your car fixed or leave it but do not use this!

I have a 2011 Chevy Silverado. People told me, these older vehicles, always burn oil and smoke. I started using this product a couple years ago correctly with my oil changes or whenever it needs to be topped off. So far it’s working, no smoking, and the little tapping noises of ceased. I’m surprised how fast it started working. I highly recommend this product.