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

I swear by these if I have a leak that I need to bandaid until I can properly address it. Like a minor head gasket issue, or a minor radiator and heater core leak. Will buy you time to get it repaired properly.

These coolant sealing tablets fix a variety of leaks. My water pump weepage seguayed into a leak. I had to fill my reservoir on a daily basis! As the Water pump replacement entails the removal of the timing belt, I decided to try these tablets. Simply crush them and deposit into coolant tank or radiator if you have a non pressurized reservoir. Worked like a charm. 3 months later, and no more leak. Always carry these in my vehicles. Give them to friends and loved ones.

Good product, works well!

This is the real thing recommended when you do repairs to GM vehicles.

Been using these for years on all of my cars. Older cars tend to weep coolant, and these tablets are a good solution, especially after a coolant flush. I start with one tablet and work my way up to no more than three to solve any weeping at the freeze plugs, hose flanges, or water pump. On discount, these tablets are a good buy. Some say they are the same as the "Bars" products, but I have a lifetime boycott on "Bars" products for ruining a heater core and a radiator in the past. Neither of which have happened with the AC Delco tablets. Maintain your cooling systems and these will work fine.

Used and it. It's completely waste of money.

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).

Recommended by gm when you change your coolant "dexcool" in your aluminum engine block. After 19 years my zo6 is happy!!!

It did a great job plugging the pinhole leak in my heater core up until it plugged my radiator, causing my radiator to blow up at high rpm, and then my water pump seals failed immediately after the rad. Both were just under 100k miles and the system was pretty clean. Was not expecting that result.

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.

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.

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

Note: I received AC Delco tablets which is fine because they are all really re-branded Bar's tablets.Make sure you are using 1-1.5 g per liter of final coolant mix. If your coolant is aging anyway you should probably just drain the old stuff while the engine is cold (most GM cars have a petcock either on the passenger side or driver side). On my husband's 3.5L Pontiac G6 2008 it is on the driver side. On my 2008 Saturn Vue 2.4L XE it is on the passenger side. After letting the coolant drain completely (note you are not draining the engine block by this method), close the petcock. Fill the coolant system with distilled (not tap) from the coolant reservoir (or radiator cap if your vehicle has one). The minerals in tap water can corrode aluminum radiators.Next, once the system is full to the cold fill line there will be lots of air in the system. Turn on the engine with the heat on (turn to the hottest setting but do not turn the fan on). Keep the coolant cap on so air can purge from the system. Some vehicles have a bleeder screw but my two did not. Once the engine gets to temperature by running at 2000 RPM in short cycles the cooling fans will start. Make sure you are not overheating your engine as this is a possibility if your water level is low and air is still in the system so take it slow. If your engine temperature is starting to overheat turn off the engine and wait a bit. After the fans start running and the level is topped off of water let the engine run for 5-10 more minutes. This means that the engine block is circulating. Since water has a lower boiling point than a coolant mix you might boil over the top of the reservoir so be careful.Let the engine cool after turning off the engine. After that drain the coolant system with the petcock into a large drain pan. You may want to repeat this one more time with more distilled water if you really want to get out most of the old coolant. You are going to need 4-5 gallons of distilled water (roughly 80 cents a gallon from your local walmart or supermarket). Once the water is done draining close the petcock. Start refilling with full 100% coolant for most and 50% coolant to finish it off. Ideally you should crush the coolant tablets in a separate container then mix it with coolant you are adding into a radiator hose. The risk with using the tablets in the reservoir is that they can plug the reservoir or upper hoses. In my GM cars I used Prestone extended life (dexcool compatible orange stuff). They also make hydrometers (Prestone, Peak make one) to ensure you have the correct ratio of coolant to water (should be about 50/50 but 60/40 may be good as well if you are in areas that it gets very cold). Too little coolant is not good either as you may be more prone to corrosion. There are also coolant testing strips that are alternatives). Repeat the engine idling with the cap off until you get all the air into the system. Dexcool will destroy the engine with gunk if there is air in the system, the heat will not work, and you want to avoid that. Always keep the coolant reservoir to the max level. Ensure full burping of the system.Note: most manufacturers including GM do not advise these tabs for normal maintenance. You shouldn't really add this to your car unless it was recommended by the manufacturer or you have a problem. There were older GM vehicles (Northstar engines) that you needed these tablets but now the problem is no longer present in newer cars. The G6 I have isn't leaking anymore (so far) so it looks like the stuff is working.