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20 Best Engine Coolant Stop Leak (2023 Updated)

Engine coolant stop leak is a product that is added to the coolant system to help seal any leaks that may be present. It is usually a temporary fix and is not a permanent solution.

20 Best Engine Coolant Stop Leak

Product Image Product Name Features Price

Bar's Leaks Liquid Aluminum Radiator Stop Leak 16.9oz

  • Safely Seals Leaks
  • Stops Overheating
  • Reduces Water Temperature

Bar's Leaks – 11 oz. Radiator Stop Leak

  • Works with any color antifreeze
  • Stops leaks and drips from wear and age
  • Harmless to rubber, aluminum & other metals

Liqui Moly 20132 – Radiator Stop Leak

  • LIQUI MOLY Radiator Stop-Leak completely seals such leaks immediately with ease.
  • Secures the combustion chamber from damages caused by coolant admission.

Bar's Leaks – 18oz. Block Seal Liquid Copper Intake & Radiator Stop

  • One Step, No Draining Required
  • Antifreeze Compatible Sodium Silicate Formula
  • Permanent Cooling System Repair

Bar's Leaks Pelletized Radiator Stop Leak 11oz

  • Seals leaks
  • Conditions cooling system
  • Inhibits rust and corrosion

K Seal Heavy Duty Permanent Coolant Leak Sealer – 16 oz jug

  • Item Weight 544 g
  • Product Dimensions 15 x 10.4 x 4.8 cm
  • Item Weight 544 gm

Bar's Leaks Radiator Stop Leak Tablets

  • Seals leaks
  • Conditions cooling system
  • Inhibits rust and corrosion

Bar's Leaks Engine Repair – 16.9 oz

  • Increases oil pressure
  • Reduces friction
  • Helps clean internal parts

Bar's Leaks Cooling System Repair – 16.9 fl oz bottle

  • Scientifically Formulated To Stop Coolant Leaks, Thereby Reducing Antifreeze Loss
  • Cooling System Repair Stops Overheating And Reduces Water Temperature

Wynns WY55864 Radiator Stop Leak 325ml

  • Stops and prevents leaks in the radiator and cooling
  • Stops and prevents leaks
  • Stops head gasket leaks

Liqui Moly Radiator Stop Leak 250ml

  • suitable for aluminum radiators.
  • permanently and reliably seals hairline cracks and small leaks.
  • no negative side effects on the water pump or heating circuit.

K-Seal Coolant Leak Repair, Head Gasket Sealant, Block Sealer, Radiator, Heater Core Stop Leak, ST5501

  • Advanced ceramic forumla Product Features: Anyone can use this product.
  • No Flushing or Draining.
  • You can even pour into the overflow tank. Mixes w/all types of antifreeze Just shake, pour & go.

K-Seal ST5501 Permanent Coolant Leak Repair – 8 oz bottle

  • No Flushing. Just shake, pour and go!
  • Mixes with all types of Antifreeze.
  • Multi Purpose ONe Step & Permanent.

Atomex Stop Leak Radiator Cooling System Additive

  • Latest generation product designed to eliminate leaks in the cooling system.
  • Tightens loose gaskets of the cylinder block, etc.

AlumaSeal ASBPI12 Radiator Stop Leak Powder Blister Card – 20 G

  • Inhibits rust
  • Lubricates water pump
  • Quick permanent seal

Rislone Block Seal Stop Leak

  • 1 Step Sealer
  • Antifreeze Compatible
  • Permanently Repairs Larger Leaks

CRC – 401214×6 – K&W Instant Cooling System Stop Lea

  • ItemNumber#C28401214X6
  • Using Nanotechnology, This Product Fills In Cracks And Crevices Other Products Can’t, Making A Stronger, More Solid Bond Than Competitors’ Products

Holts SEALit Permanent Professional Coolant Leak Repair Just Pour & Go

  • SEALit is easy to use – simply pour and fix with no need to drain or flush the system, turning leak repairs into a quick job.
Bar's Leaks Liquid Aluminum Radiator Stop Leak 16.9oz
  • Safely Seals Leaks
  • Stops Overheating
  • Reduces Water Temperature
Bar's Leaks – 11 oz. Radiator Stop Leak
  • Works with any color antifreeze
  • Stops leaks and drips from wear and age
  • Harmless to rubber, aluminum & other metals
Liqui Moly 20132 – Radiator Stop Leak
  • LIQUI MOLY Radiator Stop-Leak completely seals such leaks immediately with ease.
  • Secures the combustion chamber from damages caused by coolant admission.
Bar's Leaks – 18oz. Block Seal Liquid Copper Intake & Radiator Stop
  • One Step, No Draining Required
  • Antifreeze Compatible Sodium Silicate Formula
  • Permanent Cooling System Repair
Bar's Leaks Pelletized Radiator Stop Leak 11oz
  • Seals leaks
  • Conditions cooling system
  • Inhibits rust and corrosion
K Seal Heavy Duty Permanent Coolant Leak Sealer – 16 oz jug
  • Item Weight 544 g
  • Product Dimensions 15 x 10.4 x 4.8 cm
  • Item Weight 544 gm
Bar's Leaks Radiator Stop Leak Tablets
  • Seals leaks
  • Conditions cooling system
  • Inhibits rust and corrosion
Bar's Leaks Engine Repair – 16.9 oz
  • Increases oil pressure
  • Reduces friction
  • Helps clean internal parts
Bar's Leaks Cooling System Repair – 16.9 fl oz bottle
  • Scientifically Formulated To Stop Coolant Leaks, Thereby Reducing Antifreeze Loss
  • Cooling System Repair Stops Overheating And Reduces Water Temperature
Wynns WY55864 Radiator Stop Leak 325ml
  • Stops and prevents leaks in the radiator and cooling
  • Stops and prevents leaks
  • Stops head gasket leaks
Liqui Moly Radiator Stop Leak 250ml
  • suitable for aluminum radiators.
  • permanently and reliably seals hairline cracks and small leaks.
  • no negative side effects on the water pump or heating circuit.
K-Seal Coolant Leak Repair, Head Gasket Sealant, Block Sealer, Radiator, Heater Core Stop Leak, ST5501
  • Advanced ceramic forumla Product Features: Anyone can use this product.
  • No Flushing or Draining.
  • You can even pour into the overflow tank. Mixes w/all types of antifreeze Just shake, pour & go.
K-Seal ST5501 Permanent Coolant Leak Repair – 8 oz bottle
  • No Flushing. Just shake, pour and go!
  • Mixes with all types of Antifreeze.
  • Multi Purpose ONe Step & Permanent.
Atomex Stop Leak Radiator Cooling System Additive
  • Latest generation product designed to eliminate leaks in the cooling system.
  • Tightens loose gaskets of the cylinder block, etc.
AlumaSeal ASBPI12 Radiator Stop Leak Powder Blister Card – 20 G
  • Inhibits rust
  • Lubricates water pump
  • Quick permanent seal
Rislone Block Seal Stop Leak
  • 1 Step Sealer
  • Antifreeze Compatible
  • Permanently Repairs Larger Leaks
CRC – 401214×6 – K&W Instant Cooling System Stop Lea
  • ItemNumber#C28401214X6
  • Using Nanotechnology, This Product Fills In Cracks And Crevices Other Products Can’t, Making A Stronger, More Solid Bond Than Competitors’ Products
Holts SEALit Permanent Professional Coolant Leak Repair Just Pour & Go
  • SEALit is easy to use – simply pour and fix with no need to drain or flush the system, turning leak repairs into a quick job.

1. Bar’s Leaks Liquid Aluminum Radiator Stop Leak 16.9oz

Bar's Leaks Liquid Aluminum Radiator Stop Leak 16.9oz

  • Safely Seals Leaks
  • Stops Overheating
  • Reduces Water Temperature

Check Latest Price

Sold By Price
Amazon.com
Walmart
AutoZone
Ace Hardware

Product Details

Specifications

Details
Excluded Ship States No
Item has MSDS (SDS)? Y
Special Instructions Use 1/2 (half) bottle in a small cooling system, such as 4 cylinders with no A/C. Use 1 (one) bottle for regular size systems, most 4, 6, 8 and 10 cylinder engines.
Item is Shipped at this Packaging Level N
Information Effective Date 2011-06-27 12:00:00

Reviews From Real Customers

Precioso
Joey
Watterson

2. Bar’s Leaks – 11 oz. Radiator Stop Leak

Bar's Leaks - 11 oz. Radiator Stop Leak

  • Works with any color antifreeze
  • Stops leaks and drips from wear and age
  • Harmless to rubber, aluminum & other metals

Check Latest Price

Sold By Price
Amazon.com – Seller
Walmart
AutoZone
Ace Hardware

Product Details

Specifications

Details
Product Type Stop Leak Concentrate
Container Size 11 oz
Brand Name Bar’s Leaks

Reviews From Real Customers

Kurt P
oguz1
foster

3. Liqui Moly 20132 – Radiator Stop Leak

Liqui Moly 20132 - Radiator Stop Leak

  • LIQUI MOLY Radiator Stop-Leak completely seals such leaks immediately with ease.
  • Secures the combustion chamber from damages caused by coolant admission.
  • For all cooling water and heating systems with and without water filters.

Check Latest Price

Sold By Price
Amazon.com – Seller
ECS Tuning
FCP Euro
Turner Motorsport

Product Details

Specifications

Details
Length 6.5 in
Height 2.5 in
Width 2.5 in
Weight 0.7 lb

Reviews From Real Customers

Br3adpan
finglonga
2trippers

4. Bar’s Leaks – 18oz. Block Seal Liquid Copper Intake & Radiator Stop

Bar's Leaks - 18oz. Block Seal Liquid Copper Intake & Radiator Stop

  • One Step, No Draining Required
  • Antifreeze Compatible Sodium Silicate Formula
  • Permanent Cooling System Repair
  • Works With All Types Of Antifreeze Or Water

Check Latest Price

Sold By Price
Amazon.com
eBay
Walmart
AutoZone

Product Details

Specifications

Details
Item has MSDS (SDS)? Y
Special Instructions Use 1/2 (half) bottle in a small cooling systems, such as 4 cylinders with no A/C. Use 1 (one) bottle for regular size systems, which are most 4, 6, 8 and 10 cylinder engines. For larger systems, use 1 bottle for every 6 gallons of cooling system capacity.
Package Weight 18
Package Weight UOM OZ
Package Size 18 oz

Reviews From Real Customers

JP [Crazytekkie] (Crazytekkie)
Frustrated
Jonas

5. Bar’s Leaks Pelletized Radiator Stop Leak 11oz

Bar's Leaks Pelletized Radiator Stop Leak 11oz

  • Seals leaks
  • Conditions cooling system
  • Inhibits rust and corrosion
  • Lubricates water pump seals
  • Helps control electrolysis

Check Latest Price

Sold By Price
Amazon.com
eBay
Walmart
AutoZone

Product Details

Specifications

Details
Item has MSDS (SDS)? Y
Special Instructions Use 1 bottle for 6, 8 and 10 cylinder gas or diesel engines. For 4 cylinder engines, use 1/2 of liquid and pellets. One bottle treats systems up to 4 gallons.
Package Weight 11
Package Weight UOM OZ
Package Size 11 oz

Reviews From Real Customers

2015-steif
JoeCLEAN

6. K Seal Heavy Duty Permanent Coolant Leak Sealer – 16 oz jug

K Seal Heavy Duty Permanent Coolant Leak Sealer - 16 oz jug

  • Item Weight 544 g
  • Product Dimensions 15 x 10.4 x 4.8 cm
  • Item Weight 544 gm

Check Latest Price

Sold By Price
Amazon.com
eBay
Walmart
JBTools.com

Product Details

Specifications

Details
Product Dimensions 5.9 x 4.1 x 1.9 inches
Country of Origin USA
Is Discontinued By Manufacturer No

Reviews From Real Customers

H.G.R.
D.B.P.
K.

7. Bar’s Leaks Radiator Stop Leak Tablets

Bar's Leaks Radiator Stop Leak Tablets

  • Seals leaks
  • Conditions cooling system
  • Inhibits rust and corrosion
  • Lubricates water pump seals
  • Helps control electrolysis

Check Latest Price

Sold By Price
Amazon.com – Seller
eBay
NAPA Auto Parts
Advance Auto Parts

Product Details

Reviews From Real Customers

Mark W.
TahoeJoe

8. Bar’s Leaks Engine Repair – 16.9 oz

Bar's Leaks Engine Repair - 16.9 oz

  • Increases oil pressure
  • Reduces friction
  • Helps clean internal parts
  • Quiets noise
  • Reduces oil consumption

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Sold By Price
Amazon.com
eBay
Walmart
AutoZone

Product Details

Specifications

Details
Item has MSDS (SDS)? Y
Special Instructions If using Engine Repair when changing oil, add entire contents of bottle after filter is changed. Then refill with manufacturer’s recommended oil to proper level. Drive vehicle and recheck oil level.
Net Packaged Quantity 1 BO
Package Size 16 oz
Flash Point 380 °F

Reviews From Real Customers

B.L.

9. Bar’s Leaks Cooling System Repair – 16.9 fl oz bottle

Bar's Leaks Cooling System Repair - 16.9 fl oz bottle

  • Scientifically Formulated To Stop Coolant Leaks, Thereby Reducing Antifreeze Loss
  • Cooling System Repair Stops Overheating And Reduces Water Temperature
  • Works With Any Color Antifreeze
  • Reinforced With Carbon Fiber

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Sold By Price
Amazon
Walmart
AutoZone
NAPA Auto Parts

Product Details

Specifications

Details
Size 1 Pack

Reviews From Real Customers

Snobordnut
Nikkolas
TonyaMac

10. Wynns WY55864 Radiator Stop Leak 325ml

Wynns WY55864 Radiator Stop Leak 325ml

  • Stops and prevents leaks in the radiator and cooling
  • Stops and prevents leaks
  • Stops head gasket leaks
  • Protects the cooling system
  • Anti-corrosion

Check Latest Price

Sold By Price
Amazon
eBay
Bonanza – roxy media’s booth
NxDeals.com

Product Details

Specifications

Details
Product Genre/Category Auto

Reviews From Real Customers

GSI SID
Lee337
Garjay

11. Liqui Moly Radiator Stop Leak 250ml

Liqui Moly Radiator Stop Leak 250ml

  • suitable for aluminum radiators.
  • permanently and reliably seals hairline cracks and small leaks.
  • no negative side effects on the water pump or heating circuit.
  • for preventive use For all cooling water and heating systems with and without water filters.

Check Latest Price

Sold By Price
Amazon
MicksGarage.com

Product Details

Reviews From Real Customers

malco-birc

12. K-Seal Coolant Leak Repair, Head Gasket Sealant, Block Sealer, Radiator, Heater Core Stop Leak, ST5501

K-Seal Coolant Leak Repair, Head Gasket Sealant, Block Sealer, Radiator, Heater Core Stop Leak, ST5501

  • Advanced ceramic forumla Product Features: Anyone can use this product.
  • No Flushing or Draining.
  • You can even pour into the overflow tank. Mixes w/all types of antifreeze Just shake, pour & go.
  • Works in just minutes Works on Head Gaskets, Radiator, Heater Cores, Freeze Plugs, Water Pump Casings, Cylinder Heads & Cracked Blocks.

Check Latest Price

Sold By Price
Amazon
eBay
Walmart
NAPA Auto Parts

Product Details

Reviews From Real Customers

Martin
C.J.
Sirstylish

13. K-Seal ST5501 Permanent Coolant Leak Repair – 8 oz bottle

K-Seal ST5501 Permanent Coolant Leak Repair - 8 oz bottle

  • No Flushing. Just shake, pour and go!
  • Mixes with all types of Antifreeze.
  • Multi Purpose ONe Step & Permanent.

Check Latest Price

Sold By Price
Amazon
eBay
Agri Supply
ToolTopia.com

Product Details

Specifications

Details
Units in Package 1
Unit Size 8 oz

14. Atomex Stop Leak Radiator Cooling System Additive

Atomex Stop Leak Radiator Cooling System Additive

  • Latest generation product designed to eliminate leaks in the cooling system.
  • Tightens loose gaskets of the cylinder block, etc.
  • Completely eliminates leaks, reliably and permanently seals cracks and minor (up to 0.9 mm) damages in pipelines and joints.
  • Protects the cooling system from rust and corrosion for a long period.
  • Universal in application for gasoline and diesel engines of cars and other equipment.

Check Latest Price

Sold By Price
Amazon
eBay
Walmart – Xado Tech LLC
XADO

Product Details

Reviews From Real Customers

menakajd
plasterer0170
xado-france.com

15. AlumaSeal ASBPI12 Radiator Stop Leak Powder Blister Card – 20 G

AlumaSeal ASBPI12 Radiator Stop Leak Powder Blister Card - 20 G

  • Inhibits rust
  • Lubricates water pump
  • Quick permanent seal
  • Compatible w/all antifreeze including extended life coolants
  • Will not clog cooling systems

Check Latest Price

Sold By Price
Amazon
Ace Hardware
Advance Auto Parts
Long Beach Ace Hardware

Product Details

Specifications

Details
Recommended Surface Type Aluminum
Container Size 0.7 oz
Brand Name AlumAseal
Product Type Stop Leak Radiator Sealer

Reviews From Real Customers

Pablo
Advance Auto Parts
Nodrog

16. Rislone Block Seal Stop Leak

Rislone Block Seal Stop Leak

  • 1 Step Sealer
  • Antifreeze Compatible
  • Permanently Repairs Larger Leaks
  • Compatible Will All Types of 50/50 Mix Antifreeze
  • Made in the USA

Check Latest Price

Sold By Price
Amazon
eBay
bigamart.com

Product Details

Specifications

Details
dimensions 16.77 x 16.77 x 47.74 cm; 559.99 Grams

Reviews From Real Customers

LetsGo
Jack2011

17. Liqui Moly 20132 Radiator Stop Leak, 250 ml

Liqui Moly 20132 Radiator Stop Leak, 250 ml

Check Latest Price

Sold By Price
Amazon
eBay – speedysales715

Product Details

Specifications

Details
Weight 0.7 lb

18. CRC – 401214×6 – K&W Instant Cooling System Stop Lea

CRC - 401214x6 - K&W Instant Cooling System Stop Lea

  • ItemNumber#C28401214X6
  • Using Nanotechnology, This Product Fills In Cracks And Crevices Other Products Can’t, Making A Stronger, More Solid Bond Than Competitors’ Products
  • Compatible With All Types Of Anti-Freeze

Check Latest Price

Sold By Price
Amazon
eBay
Walmart
AutoZone

Product Details

Specifications

Details
Appearance Lumpy Copper Liquid
Odor Mild
Container Size 15 fl oz (US)
Acts as Stop Leak No
SDS Required Yes

Reviews From Real Customers

Autologous1
Cuso
Rodger76

19. Holts SEALit Permanent Professional Coolant Leak Repair Just Pour & Go

Holts SEALit Permanent Professional Coolant Leak Repair Just Pour & Go

  • SEALit is easy to use – simply pour and fix with no need to drain or flush the system, turning leak repairs into a quick job.
  • Professional and permanent repair.
  • No clogging or damaging effect.
  • Corrosion protection.

Check Latest Price

Sold By Price
Amazon
eBay

Product Details

Reviews From Real Customers

dfordcapri
mtb_123
2sunnyside

20. K-Seal ST5501 Multi Purpose One Step Permanent Coolant Leak RepairFixes Cracks and Leaks in Radiator, Head Gasket, Freeze Plugs, Cylinder heads,.., by

K-Seal ST5501 Multi Purpose One Step Permanent Coolant Leak RepairFixes Cracks and Leaks in Radiator, Head Gasket, Freeze Plugs, Cylinder heads,.., by

Check Latest Price

Sold By Price
Amazon
Walmart

Product Details

Reviews From Real Customers

Morpheus

Conclusion

If your car is low on engine coolant, you may be tempted to add a stop leak product to seal the leaks. However, stop leak products can actually cause more problems than they solve. The sealant can clog up your cooling system, leading to overheating and engine damage.

It can also react with other chemicals in the coolant, causing corrosion. If you have a leak, it’s best to have it repaired by a professional.

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