We may earn a commission if you make a purchase through one of our links. Learn more

Auto Maintenance & Care

Best Radiator Stop Leak Products

Radiator Stop Leak products are somewhat debated as to their effectiveness, or whether they’re worth using at all. Although they generally are able to temporarily stop a leak in some cars, they’re not a long term solution as they can cause more issues further down the line by clogging up engine systems. Some people do use these products without any issue, however, and it's worth knowing which the best are in the event that you need a stop gap measure.

We've chosen the best radiator stop leak products that are well-rated for their effectiveness, and have been around long enough to note any long-term issues likely to arise following their use. Each of the following products is relatively affordable and simple to use, making them good to have on hand for emergency situations.

Bars Leaks Radiator Stop Leak Concentrate (1196)

The Bar's Leaks brand is the most popular when it comes to cooling system products, thanks to their effectiveness and accessibility at most stores. They have multiple products for varying degrees and types of leaks, with their Radiator Stop Leak Concentrate being suited for stopping minor cooling system leaks. This product is good for radiator, heater core, and freeze plug leaks, while being compatible with all types of antifreeze. A single bottle can treat up to four gallons, making this a cost-effective option for temporarily sealing leaks.

K-Seal ST5501 Multi Purpose One Step Permanent Coolant Leak Repair

This stop leak from K-Seal offers a simple and effective temporary solution to a radiator leak. Although the product makes claims of permanent repair, no stop leak product is really ideal as a long-term solution. K-Seal is easy to use as you simple shake the bottle, pour it in, and then you're good to go. Effective for leaks in the radiator, head gasket, heater core, and more, this multi-purpose product is convenient to have around as a band aid-style fix. K-Seal mixes with all types of antifreeze.

Dike Temporary Radiator Stop Leak

Dike Temporary Radiator Stop Leak is a good product to have on hand for emergency situations. This stop leak is compatible with all coolants, and can be used to seal leaks in the radiator, heater core, head gasket, and hose connections. Although this particular product can prove somewhat more difficult to find in stores, users find that it works quickly and effectively to stop leaks. Dike Temporary Radiator Stop Leak is simple to use and reasonably affordable.

AlumAseal ASBPI12 Radiator Stop Leak Powder Blister Card

This popular brand has been around for a long time. AlumAseal radiator stop leak products have been used for years to provide a temporary fix for a leaking radiator or heater core. The AlumAseal Radiator Stop Leak Powder Blister Card is quick and easy to use; simply pop it in and drive off. This product is compatible with all antifreeze and coolant types, as well as being safe with all metal, plastic, and rubber parts. Its widespread availability and affordable price make it an accessible option.

CRC 401211 Heavy Duty Radiator Stop Leak

The CRC Heavy Duty Radiator Stop Leak has been formulated to quickly and easily provide a temporary solution to cracks or leaks in your radiator or heater core. This product is safe for use with all standard coolant and antifreeze types, and can be used with any type of radiator and heater core. Although not VOC compliant for California vehicles, this radiator stop leak is a good option to have on hand in case of an emergency. CRC Heavy Duty Radiator Stop Leak is easy to use as you simply pour it in and drive.

Go to top