K-Seal Heavy Duty ST5516 Antifreeze & Coolant Stop Leak 16oz Bottle Treats Large Trucks, RVs, Bus and Tractors
K-Seal Heavy Duty ST5516 Antifreeze & Coolant Stop Leak 16oz Bottle Treats Large Trucks, RVs, Bus and Tractors
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K-Seal

K-Seal Heavy Duty ST5516 Antifreeze & Coolant Stop Leak 16oz Bottle Treats Large Trucks, RVs, Bus and Tractors

4.1 stars out of 43 reviews
(4.1)|
43 ratings
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Key item features

  • Heavy-Duty Repair: One-step permanent coolant leak repair for heavy-duty vehicles, designed for large cooling systems with capacities greater than 20 quarts.
  • Versatile Compatibility: Compatible with all standard antifreeze and coolant types, and safe for use with metal, plastic, rubber, and composite cooling system components.
  • Rapid Sealing: Begins sealing coolant leaks quickly as the product circulates, delivering fast-acting performance without requiring extended downtime.
  • Extensive Application: Ideal for large trucks, RVs, tractors, agricultural equipment, and commercial vehicles, formulated for systems up to 50 quarts.
  • Reliable Performance: Provides a durable, long-lasting repair for coolant leaks under heavy-duty operating conditions, sealing cracks, pinholes, and porosity.
  • Simple Application: No draining or flushing required; simply shake, pour, and go, working while the engine is running without system disassembly.
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Current price is $19.66$1.23/fl oz
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Columbus, 43215
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Customer ratings & reviews

4.1 out of 5 stars
stars43 ratings24 reviews
How item rating is calculated
  1. 5 stars67% (29)
  2. 4 stars2% (1)
  3. 3 stars14% (6)
  4. 2 stars2% (1)
  5. 1 star14% (6)

Reviews summary

Pros
  • : Seals small to moderate-sized leaks.
  • : Offered at a cost that is not too high or too low.
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Showing 1-3 of 24 reviews

Jul 11, 2025
CDREO
Sold byNature's HealthDelivered byWalmart
5 out of 5 stars review

Verified Purchase

Stops leaks

saw some brown residue in oil cap which is an indicator of water in the motor oil. As a precaution I poured the solution and let it run for a while. That was about 4 months ago and I haven't seen any signs of trouble.

Incentivized Review
Helpful?18DAI2B3QSTO30391262
Sep 27, 2020
HYUNGJO
5 out of 5 stars review

Verified Purchase

Wonderful Radiator Sealer

This is very good sealer. Last February My contractor ordered a New Diesel Generator($3376.00) to England. But the Factory could not send because of the COVID 19. So I applied this item and worked out to stop LEAKING.

Helpful?18DAI2B3QSTO30391262
Oct 9, 2024
WalmartCustomer
5 out of 5 stars review

Verified Purchase

K-Seal Heavy Duty Coolant Leak Sealer is a lifesaver! I used the 16 fl oz bottle on my RV, and it worked perfectly to stop a serious coolant leak. What impressed me the most was how quickly it sealed the leak and how easy it was to use—just pour it into the system, and it does the rest. It's been a few weeks now, and my engine is running smoothly with no more overheating issues. This product definitely saved me from an expensive repair bill, and I highly recommend it to anyone with large trucks, RVs, or tractors. Five stars for sure!

Helpful?18DAI2B3QSTO30391262