---
product_id: 285495147
title: "ST5516 Heavy-Duty Multi-Purpose One Step Permanent Coolant Leak Repair, 8oz, Pour and Go, Mixes with All Antifreeze, No Flushing Required"
brand: "k-seal"
price: "340 Lei"
currency: RON
in_stock: true
reviews_count: 7
category: "K Seal"
url: https://www.desertcart.ro/products/285495147-st5516-heavy-duty-multi-purpose-one-step-permanent-coolant-leak
store_origin: RO
region: Romania
---

# One-step, no flushing needed Heavy-duty for large engines Seals leaks in minutes ST5516 Heavy-Duty Multi-Purpose One Step Permanent Coolant Leak Repair, 8oz, Pour and Go, Mixes with All Antifreeze, No Flushing Required

**Brand:** k-seal
**Price:** 340 Lei
**Availability:** ✅ In Stock

## Summary

> 🚀 Seal leaks fast, drive worry-free—because downtime is not an option!

## Quick Answers

- **What is this?** ST5516 Heavy-Duty Multi-Purpose One Step Permanent Coolant Leak Repair, 8oz, Pour and Go, Mixes with All Antifreeze, No Flushing Required by k-seal
- **How much does it cost?** 340 Lei with free shipping
- **Is it available?** Yes, in stock and ready to ship
- **Where can I buy it?** [www.desertcart.ro](https://www.desertcart.ro/products/285495147-st5516-heavy-duty-multi-purpose-one-step-permanent-coolant-leak)

## Best For

- k-seal enthusiasts

## Why This Product

- Trusted k-seal brand quality
- Free international shipping included
- Worldwide delivery with tracking
- 15-day hassle-free returns

## Key Features

- • **Instant Leak Fix:** Permanently seals radiator, head gasket, freeze plugs & more in minutes
- • **Effortless Application:** Shake, pour & go—no draining or flushing required
- • **Heavy-Duty Reliability:** Engineered for commercial, agricultural & industrial engines
- • **Universal Compatibility:** Works seamlessly with all antifreeze types for any vehicle
- • **Mechanic-Trusted Formula:** Non-corrosive, clog-free, ASTM D3147 verified for lasting performance

## Overview

K-Seal ST5516 Heavy-Duty is a professional-grade, one-step coolant leak repair solution that permanently seals cracks and holes in water-cooled engines. Compatible with all antifreeze types, it requires no system draining or flushing and is engineered for heavy-duty commercial and agricultural vehicles. Trusted by mechanics worldwide and independently tested to ASTM standards, it delivers fast, reliable, and clog-free performance to extend engine life and prevent costly repairs.

## Description

Experience the ultimate solution to coolant leaks with the K-Seal ST5516 HD, a multi-purpose, one-step permanent coolant leak repair. Our powerful formula works seamlessly with all antifreeze, making it a universal fit type for all your needs. No need for draining or flushing your system. This heavy-duty sealer was designed specifically for HGVs, tractors, heavy plant and other commercial vehicles. The K-Seal ST5516 HD, also known as a head gasket stop leak, works by sealing leaks efficiently and permanently. It also doubles as a radiator stop leak, effectively putting an end to any leaks in your radiator. The permanent leak sealer is easy to use - just shake, pour, and go. This product excels in fixing cracks and leaks in several components including the radiator, head gasket, freeze plugs, cylinder heads, heater core, water pump casing, and engine blocks. With a single 8 fluid ounce bottle of our coolant leak sealer, you can treat up to 20 quarts cooling capacity. This heavy duty stop leak sealant is a must-have for all your coolant leak issues. So, forget your coolant leak worries with the K-Seal ST5516 HD. Experience the power of a seal stop leak that stops leaks permanently, offering peace of mind and extended life for your vehicle's cooling system. Trust the K-Seal coolant leak repair for a lasting solution to all your coolant leak problems.

Review: Very effective with intake gasket coolant leak - I had an unsatisfactory result with one of my cars I earlier reviewed. However, I had a visible gakset leak between the plastic intake manifold and cylinder head in 2007 Town Car, and was about to remove it for servicing until I thought, let me give K-Seal another shot since I had a small quantity left. The result was magic! The leak is gone, and been running dry and clean for a month now.
Review: Good product. Quick delivery. - Happy with the product.

## Features

- FIX IT FAST: Our multi-purpose solution works in minutes to quickly & permanently seal leaks in the radiator, head gasket, freeze plugs, block, heater matrix & water pump of heavy duty vehicles. Fixes most leaks in water-cooled engines
- STOP HOLES & CRACKS: With 1 step our unique formula will seek out each hole & crack, permanently sealing them, without any adverse impact on the efficiency of your engine cooling
- EASY TO USE: K-Seal couldn't be simpler & requires no draining or flushing; just shake, pour & go - shake the bottle, add the fluid to your coolant system & run your engine as normal
- HEAVY DUTY PERFORMANCE: Engineered for large engines & industrial use; suitable for commercial or agricultural vehicles. A permanent repair for the lifetime of the engine. Compatible with all types of antifreeze coolant
- PROFESSIONAL-GRADE RELIABILITY: Trusted by mechanics, our non-corrosive sealer delivers a durable & long-lasting repair, without clogging your cooling system. A cost-effective solution to engine coolant leaks, enhancing the reliability & performance of your vehicle’s cooling system. We've sold millions worldwide & are independently verified by university testing to meet ASTM D3147

## Technical Specifications

| Specification | Value |
|---------------|-------|
| ASIN | B002BJEG3U |
| Best Sellers Rank | #36,905 in Automotive ( See Top 100 in Automotive ) #98 in Antifreezes & Coolants |
| Brand | K-Seal |
| Customer Reviews | 4.4 4.4 out of 5 stars (1,483) |
| Date First Available | 7 August 2012 |
| Item Weight | 540 g |
| Item model number | ST5516HD |
| Manufacturer | Solv-Tec |
| Manufacturer Part Number | ST5516 |
| Model | ST5516HD |
| Product Dimensions | 14.99 x 10.41 x 4.83 cm; 540 g |

## Images

![ST5516 Heavy-Duty Multi-Purpose One Step Permanent Coolant Leak Repair, 8oz, Pour and Go, Mixes with All Antifreeze, No Flushing Required - Image 1](https://m.media-amazon.com/images/I/81sHDXp6ouL.jpg)

## Questions & Answers

**Q: Does it work on potentially warped heads**
A: No idea

**Q: how much do i need to pour in a diesel 1 ton cummins**
A: You need this one bottle for a Dodge 3500 hd.  I have this one bottle in my HD Freightliner 330hp MBZ engine hauling freight (54,000 lbs cap) 6 days a week and it stopped my coolant leak in the engine bay and heater core with no blockage and no.  My opinion, Many reviews say products dont work BECAUSE most people dont take care of their equipment and their vehicles are old, high mileage and no maintenance done.  None of the add to a tank products are as good as replacing with new parts but thats expensive, we get it.  This may or may not fix your problem but its a low cost gamble with a high probability of success.  Dont listen to the negative reviews.  If the problem comes back, your damage was too far gone and in need of replacement anyway.

**Q: Will this work with aluminum heads?**
A: It works equally well with cast iron or aluminum. Great Stuff. Not a long-term solution, but it will buy you a lot of time.

**Q: Tried using alumaseal, which isn't working.  will i need to flush the system before using the k-seal?**
A: I used the HD Truck bottle on my 1998 GEO Tracker ( used 1/3 of the bottle ) of K-Seal and it worked. I have used so many to no avail. To answer your question, I must have @ least 3 to 4 other sealers in my colling  system when I added K-Seal. It's been almost a year & no adverse effects having not flushed my radiator. 
Should I have flushed the radiator & the system? Yes, I should have.

## Customer Reviews

### ⭐⭐⭐⭐⭐ Very effective with intake gasket coolant leak
*by A***N on 11 March 2022*

I had an unsatisfactory result with one of my cars I earlier reviewed. However, I had a visible gakset leak between the plastic intake manifold and cylinder head in 2007 Town Car, and was about to remove it for servicing until I thought, let me give K-Seal another shot since I had a small quantity left. The result was magic! The leak is gone, and been running dry and clean for a month now.

### ⭐⭐⭐⭐⭐ Good product. Quick delivery.
*by T***Y on 30 August 2023*

Happy with the product.

### ⭐⭐⭐⭐⭐ Review
*by D***G on 18 December 2023*

I have 2015 long nose Peterbilt. Had a slow cold leak from the bottom of the radiator (only would leak as the engine cools down) then I would have to add about 1 litre of coolant the next morning. After I added this product a few weeks ago, I’ve added nothing and the coolant level is still at the top. Excellent quick fix rather than new radiator.

## Frequently Bought Together

- K-Seal ST5516 Heavy-Duty Multi-Purpose One Step Permanent Coolant Leak Repair, 16 oz, Pour and Go, Mixes with All Antifreeze, No Flushing Required
- PEAK 50/50 Prediluted Antifreeze and Coolant for All Engine Cooling Systems
- K-Seal ST3501 Pour and Go Head Gasket Sealer, 16oz, Permanent Repair for Blown Head Gaskets, Cracked Heads and Blocks

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*Product available on Desertcart Romania*
*Store origin: RO*
*Last updated: 2026-01-29*