10 Best Coolant Stop Leaks 2020

Gareth Otwell Reviewed by Gareth Otwell | Last Updated:

After analyzing 166 products, scanning 830 reviews, spending more than 36 hours of research and speaking with our test users, we think the Product Name: K-Seal ST5501 Multi Purpose One Step Permanent Coolant is the one of the Best Coolant Stop Leak on the market.

Product Name: K-Seal ST5501 Multi Purpose One Step Permanent Coolant – Best Overall Coolant Stop Leak

Product Name: K-Seal ST5501 Multi Purpose One Step Permanent Coolant
  • REPAIRS IN MINUTES: Formulated to permanently weld radiators, including hard plastic aluminum heads and blocks in old and new cars. The only car radiator and gasket sealant university tested to meet ASTM D3147. Save time/money. US Bestseller
  • SEALS CRACKS AND STOPS LEAKS: A DIY alternative to costly repairs, our coolant leak fix permanently seals cracks and holes! It quickly repairs your leaking radiator, freeze plug, heater core and water pump casing with no adverse impact on efficiency.
  • POUR AND GO: Our cooling system sealer is easy to use: just shake the bottle, add to your radiator/overflow and run the engine! Unlike some traditional products, it mixes with all types of antifreeze, absolutely no draining or flushing required.
  • SCIENTIFICALLY TESTED: Safe and effective, our cracked block repair can seal leaks up to 1/32 of an inch! Once cured, the repair withstands the high pressure of the combustion chamber, all without failing or clogging the cooling system.
  • CUSTOMER SUPPORT: If our engine coolant leak doesn't seal your head gasket, the system might be over-pressurized. Check the Technical Specification section of this page for extra instructions for a successful repair. Over 8 million bottles sold.

Bar's Leaks Liquid Aluminum Stop Leak

Bar's Leaks Liquid Aluminum Stop Leak
  • Bar's Leaks Liquid Aluminum Stop Leak seals radiator leaks. Seals freeze plug leaks. Repairs gasket leaks and heater core leaks. Lowers water temperature.
  • Seals radiator leaks
  • Seals freeze plug leaks
  • Repairs gasket leaks
  • Special Shipping Information: This item cannot be returned and has additional shipping restrictions

Genuine GM (12378255) Fluid 3634621 Cooling System Seal Tablet

Genuine GM (12378255) Fluid 3634621 Cooling System Seal Tablet
  • 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

K-Seal ST5516 HD Multi Purpose One Step Permanent Coolant Leak

K-Seal ST5516 HD Multi Purpose One Step Permanent Coolant Leak
  • Permanent coolant leak repair - Just shake, pour and go
  • Mixes with all antifreeze
  • No draining or flushing
  • Fixes cracks and leaks in radiator, head gasket, freeze plugs, cylinder heads, heater core, water pump casing and engine blocks
  • If product did not seal head gasket leak, the system might be Over-pressurized, which causes back pressure and doesn't allow the product to reach the problem area, on this page below under Technical Specification is a PDF Guide with instructions to follow to complete the repair successfully

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

Bar's Leaks 1196 Radiator Stop Leak – Best Budget Coolant Stop Leak

Bar's Leaks 1196 Radiator Stop Leak
  • Auto & Truck Maintenance
  • Works with all types and colors of anti-freeze coolant
  • Stops and seals coolant leaks
  • One bottle treats up to 4 gallons

Bar's Leaks HDC Radiator Stop Leak Tablet

Bar's Leaks HDC Radiator Stop Leak Tablet
  • Seals leaks
  • Conditions cooling system
  • Inhibits rust and corrosion
  • Lubricates water pump seals
  • Helps control electrolysis

Bar's Leaks PLT11 Pelletized HD Radiator Stop Leak

Bar's Leaks PLT11 Pelletized HD Radiator Stop Leak
  • Seals leaks
  • Conditions cooling system
  • Inhibits rust and corrosion
  • Lubricates water pump seals
  • Helps control electrolysis

Bar's Leaks J-100 Professional DiFM Cooling System Treatment – Premium Pick

Bar's Leaks J-100 Professional DiFM Cooling System Treatment
  • Seals internal, external and coolant to oil leaks
  • Stops radiator tank seal leaks
  • Inhibits the formation of rust and scale
  • Helps control electrolysis and helps neutralize pH imbalance
  • Lubricates water pump seal

ATP AT-205 Re-Seal Stops Leaks

ATP AT-205 Re-Seal Stops Leaks
  • Professional strength fast acting resealer, stops leaks fast
  • Rejuivinates all rubber seals & gaskets in engines, transmissions, power steering, differentials and hydraulic systems
  • Compatible with conventional and synthetic oils, ATF, gear oil, power steering fluids and hydraulic oil
  • Does not contain petroleum distillates, will not over-swell or breakdown seals
  • 8oz bottle will treat a 6 quart capacity, adjust accordingly

Similiar Categories