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Genuine GM (12378255) Fluid 3634621 Cooling System Seal Tablet - 4 Grams, (Pack of 5)

4.5 4.5 out of 5 stars 956 ratings
$7.52
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Purchase options and add-ons

  • Non-toxic
  • DEX-COOL compatible
  • Engine application is based on liters of volume in cooling system
  • Formulated for automotive use
  • For use with all vehicles
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Genuine GM (12378255) Fluid 3634621 Cooling System Seal Tablet - 4 Grams, (Pack of 5)
$7.52
Get it May 14 - 17
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ACDelco GM Original Equipment 10-108 Cooling System Sealing Tabs - 4 g (Pack of 5)
$4.28
Get it as soon as Tuesday, May 14
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Product Description

Original organic formula designed for use in radiator systems to seal leaks and prevent leaks due to casting porosity in engine components. Seals minor leaks and porosity in cooling systems. DEX-COOL compatible. Non-toxic.

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Amazon.com Return Policy:Amazon.com Voluntary 30-Day Return Guarantee: You can return many items you have purchased within 30 days following delivery of the item to you. Our Voluntary 30-Day Return Guarantee does not affect your legal right of withdrawal in any way. You can find out more about the exceptions and conditions here.
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Genuine GM (12378255) Fluid 3634621 Cooling System Seal Tablet - 4 Grams, (Pack of 5)

Genuine GM (12378255) Fluid 3634621 Cooling System Seal Tablet - 4 Grams, (Pack of 5)

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Genuine GM (12378255) Fluid 3634621 Cooling System Seal Tablet - 4 Grams, (Pack of 5)
Genuine GM (12378255) Fluid 3634621 Cooling System Seal Tablet - 4 Grams, (Pack of 5)
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Genuine GM Fluid 12378255 Cooling System Seal Tablet - 4 Grams, (Pack of 5)
Genuine GM Fluid 12378255 Cooling System Seal Tablet - 4 Grams, (Pack of 5)
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Price$7.52-5% $20.99
List: $21.99		-14% $6.90
Typical: $7.99		$8.01
Delivery
Get it May 14 - 17
Get it as soon as Wednesday, May 15
Get it as soon as Tuesday, May 14
Get it as soon as Wednesday, May 15
Customer Ratings
4.54.5 out of 5 stars956
4.84.8 out of 5 stars1,540
4.64.6 out of 5 stars1,179
4.64.6 out of 5 stars273
Easy to use
4.8
4.9
—
4.7
Value for money
4.6
4.7
—
4.6
Sold By
The Parts Department
Amazon.com
SubaruPartsOnline
TXN Supply

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Customer reviews

4.5 out of 5 stars
4.5 out of 5
956 global ratings

Customers say

Customers like the performance, cooling and ease of use of the auto accessory. For example, they mention it works well, it keeps the engine from over heating and it's easy to use. That said, opinions are mixed on leakage.

AI-generated from the text of customer reviews

97 customers mention81 positive16 negative

Customers like the performance of the auto accessory. They mention that it works phenomenally well in the radiator, and that it's worth a try.

"...And just like I remember, they are the business! They simply work. They have been in for approximately 6000 miles...." Read more

"...This is an awesome product that works. I would recommend giving it a try if you have an occasional drop of coolant or very small leak." Read more

"good seller" Read more

"Worked fantastic. leak in heater core made cab windows fog up and could taste antifreeze in my mouth...." Read more

22 customers mention17 positive5 negative

Customers like the cooling of the product. They say it doesn't block cooling holes and it keeps their engine from over heating. Some customers also mention that the coolant level is normal after using the pellets.

"...02/05/17 - 2,000 mile update - still solid! No coolant loss. Still happy. I was losing/replacing coolant every 350-500 miles. No more...." Read more

"...Coolant is still at proper level to this day." Read more

"...in two different cars (at least I think I did), put these in, no more antifreeze loss...." Read more

"...There was no coolant on the ground and no coolant smell. Well, I guess it must be a minor head gasket leak...." Read more

19 customers mention19 positive0 negative

Customers find the product easy to use and say it works well for a quick fix on small leaks. They also say it's simple and cost effective. Customers also mention that it works great so far and is easy to add to the radiator top tank.

"Works on minor problems but mine is too far gone for it to do any good." Read more

"These tabs work great even can temporarily seal some head gasket leaks better than any of the blue devil products or similar at auto parts stores" Read more

"...It seems to be a good safe product to put in your radiator that does not clog the heater core." Read more

"...No change in reservoir level in over 1 month. Simple and cost effective cure for an older car." Read more

12 customers mention12 positive0 negative

Customers appreciate the value of the auto accessory. They say it's a simple and cost effective cure for an older car. Some customers also say it works wonderfully and saves s huge repair fee.

"...And they are dirt cheap." Read more

"...They work well and these are the cheapest way of buying them" Read more

"...this to anyone who has a small leak it works wonderfully and saves a huge repair fee." Read more

"...Good price too" Read more

82 customers mention55 positive27 negative

Customers are mixed about the leakage. Some mention that the product stopped the leak promptly, while others say that it started to leak coolant after six months.

"...give an update after a year now (and about 20k miles) my truck is still coolant leak free! I’d call this product a permanent fix...." Read more

"...Drove it to work the next day and it don't leak anymore. It's only been three weeks but it stopped the leak ...." Read more

"...It's been four months and not a single drip has escaped...." Read more

"...I also had a very small side tank leak on the radiator which I knew about but wasn't concerned about fixing right away...." Read more

I was skeptical but thought I had nothing to lose
5 Stars
I was skeptical but thought I had nothing to lose
Backstory: 2008 Saturn Aura. Coolant leak last October... I was finding large puddles in the driveway by passenger front tire area. Dealer said waterpump. Had it done. Fast foward to this month. Same puddles appearing, same area. Could smell coolant burning after a drive. NO white smoke from exhaust. Took it back to the dealer, now they say headgasket..see attached. I call bs. On a whim, I bought these tabs.. seriously for less than $10, why not? I did have a bad experience with a sealant in my Durango though- it gummed up my radiator to the point it had to be replaced... that was a heavy, heavy liquid though. So I got these tabs, read the reviews, crushed three of them up and pre-mixed it with coolant (DEX) and added it to the overflow. I then drove the car for a solid hour with the heat on as high as I could stand. After a day or two..still a puddle the next morning, but MUCH smaller. Ok, I'm encouraged now...new car search suspended... I crushed/premixed/added the last two tabs to the overflow. It has now been a full week...no more burning coolant smell and no more puddles. I'm happy. This is my first Amazon review, but I had to share this.
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Top reviews from the United States

fluke95
5.0 out of 5 stars Wow!... Take it from an old school GM guy these work.
Reviewed in the United States on July 23, 2019
Verified Purchase
I work for Pontiac Buick GMC and Saturn throughout the 90s and 2000's. I am familiar with these tablets. They were used to seal porous heads back in the day. I have since put over a million and a half miles on multiple Chevy vans for work and in all of those miles I have occurred a few leaks in the cooling system. Some of them catastrophic... That is the case on my present 2006 with 380000 miles. I love this man and recently replace the flex plate because it was cracked. If you're not familiar with that, it will sound like a Pistons going to come out of the motor and it's just a cracked flexplate. However, getting back to the coolant loss after I replace the flexplate I noticed a tiny coolant leak coming from the rear of the block. To my dismay I found the number for outer cylinder head bolt seeping not at the gasket but at the head of the bolt. I also had a very small side tank leak on the radiator which I knew about but wasn't concerned about fixing right away. I was going through approximately a quart every 500 miles with these two leaks regularly. I was also concerned that the leak would progress and get worse and possibly even enter the cylinder. So before I scrapped the van or put a motor in it which was my only two options, I remember these tablets and decided to use them. And just like I remember, they are the business! They simply work. They have been in for approximately 6000 miles. The coolant leaks on both the radiator tank and cylinder bolt have stopped. I've heard of people saying you have to smash them up and put them in you really don't. They were designed to drop in as complete pellets. You simply have to make sure the motor is cold, and drop them in the radiator and or expansion tank. Then take it out a good long easy drive City and highway a solid 15 to 20 miles. Get it up to operating temperature. And then park it and let it cool overnight. They work. However, do you remember if you have a catastrophic failure more than the threads of a cylinder head bolt or a small side take leak on the radiator there's probably nothing that's going to help that for too long. but if it's a minor league even in the cylinder head system 46 box I highly recommend trying these before you give up!
10 people found this helpful
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T. Lee
5.0 out of 5 stars Helped stop a minor leak. Great price. Safe to use with dexcool
Reviewed in the United States on January 31, 2018
Verified Purchase
I saw these when i went to the Chevy dealership and was curious about what they were. I ended up coming on amazon and purchasing them for my 2004 Saturn Ion Redline. My radiator had developed a very small leak. Also my water pump housing would occasionally drip coolant resulting in me having to add a bit of coolant every 2 weeks. I flushed my whole coolant system first with distilled water. I then drained the distilled water and added about half a gallon of dex cool coolant. I crushed all 5 tablets and mixed them in a cup with some coolant. I then added it to my fill port and topped off my reservoir with some more coolant. After driving my car a few days and adding a bit more coolant (the car purged any trapped air thats why i had to add coolant) i havent noticed any more leaks. It is now 6 months since ive done this and still no leaks! This is an awesome product that works. I would recommend giving it a try if you have an occasional drop of coolant or very small leak.
14 people found this helpful
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Matt
5.0 out of 5 stars Fixed Coolant leaking into oil - still working after a year
Reviewed in the United States on October 3, 2020
Verified Purchase
Update 11/14/2021 - Just wanted to give an update after a year now (and about 20k miles) my truck is still coolant leak free! I’d call this product a permanent fix.

I had coolant leaking into the oil on my 2003 Silverado 4.8L, most likely through a cracked head. With the age of the truck I didn't want to put too much money into a repair but, I had to do something to try to save the engine and have always been skeptical of those leak fix in a bottle products so I decided to give this a try. I thought this was better than throwing those goopy products into the radiator with a risk of plugging things up, just to find it didn't fix the leaks anyways.

After putting 3 crushed up tablets into the radiator and driving several days to my surprise it actually sealed the leak. It has now been over 2 months and couple thousand miles and have not had to add any coolant at all.

So, in my case anyway I feel like this item is 5 stars and recommend giving it a try.
6 people found this helpful
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Top reviews from other countries

Mike
5.0 out of 5 stars Cooling pellets for minor leaks
Reviewed in Canada on October 18, 2023
Verified Purchase
These AC delco pellets are the proper ones recommended by GM in certain vehicles and they will seal minor, stubborn leaks with some risk involved.
Used it on a vehicle with what I found out later was just a loose upper rad hose and it could not completely stop the leak from the rad hose however all the leaks in the rad from before have went away within a few drives.
You must follow the instructions as too many pellets could clog your heater core and lead to very expensive issues down the road which is where you must do your research and take the risks if warranted.
Product to fix minor leaks that would otherwise require replacement of the part (ex minor radiator leaks, thermostat housing leak, cracked metal parts within the cooling system).
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Grafin
5.0 out of 5 stars Works as advertised
Reviewed in India on June 12, 2019
Verified Purchase
Used this on my Skoda Laura Tai, which had a coolant leak that led to a low coolant warning popping up every three days after top up. Used two tablets along when a liter of coolant and its held good for 10 days and counting with approx 500 kms of usage.
2 people found this helpful
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Amazon Customer
5.0 out of 5 stars did the trick
Reviewed in Canada on May 7, 2017
Verified Purchase
I had a slight anti freeze leak at back of engine and kept getting air in the heater hose and losing heat at idle in 2007 Impala. Mechanic suggested the ac seal tablets. Research said that GM put them in all new cars until it converted to dex-cool. My leak stopped and heater never lost heat rest of winter
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JBL
5.0 out of 5 stars Good ac delco product,good price.
Reviewed in Canada on January 29, 2021
Verified Purchase
Recommended by gm when you change your coolant "dexcool" in your aluminum engine block. After 19 years my zo6 is happy!!!
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Scott gould
4.0 out of 5 stars as advertised
Reviewed in Canada on August 9, 2020
Verified Purchase
helped to seal small weeper
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