---
title: "Stop Leak — $284K/yr Amazon US Niche (2026) - Flapen"
canonical_url: "https://flapen.com/research/us/automotive/stop-leak"
last_updated: "2026-08-09T18:13:36.448Z"
locale: en
meta:
description: "Niche score 43/100 · $284K/yr market · 187K searches/yr · $11.23 avg price. Doesn't clear our bar today. Data updated Jul 2026."
"og:description": "Niche score 43/100 · $284K/yr market · 187K searches/yr · $11.23 avg price. Doesn't clear our bar today. Data updated Jul 2026."
"og:title": "Stop Leak — $284K/yr Amazon US Niche (2026) - Flapen"
---
# **stop leak**
**Skip it**
Brand-locked demand (top 5 brands take 100% of clicks) — this niche doesn't clear our bar today.
Market size 50Growth 19Conversion 96Competition 11Returns 85Price range 41Avg price 44Brand share 0Review moat 37Quality gap 63
**Conversion**
**Incredible****13.6%**
search→purchase rate — share of searches ending in a sale
**Returns**
**Great****1.5%**
return rate — above 5% kills the launch gate
**Quality gap**
**Good****4.4★**
avg incumbent rating — lower means beatable quality
**Market size**
**Good****$284K**
$284K/yr · 187K searches
**Avg price**
**Okay****$11.23**
avg listing price — sweet spot $15–$100
**Price range**
**Okay****$4.10–$22.51**
cheapest to priciest tracked listing — scored on the share inside $15–$100
**Review moat**
**Okay****2,752.11**
avg incumbent reviews — the moat a new listing must climb
**Growth**
**Bad****-12.2%**
90-day search growth — must beat 0% to launch
**Competition**
**Bad****86%**
top-5 click share — a locked-up shelf
**Brand share**
**Bad****100%**
top-5 brand share — brand-locked demand
According to Flapen's Amazon United States niche tracking, stop leak is a $284K/yr Amazon United States market (187K searches/yr). The top 5 brands hold 100% of demand. Demand peaks in Aug. Verdict: Skip it — 43/100.
Data updated Jul 8, 2026 · scored weekly · [~~How we score niches ~~](https://flapen.com/research/methodology)
## **stop leak market data**
- **Units sold / yr**
- **20K–25K**
- avg 1,500–2,000/product
- **Revenue / yr**
- **$225K–$281K**
- units × avg price
- **Conversion rate**
- **13.6%**
- **Avg BSR**
- **#8**
- **Page quality**
- **0%**
- **Prime**
- **100%**
- **Sponsored**
- **100%**
- **Out of stock**
- **0.0%**
- **Avg brand age**
- **96 months**
- **Avg seller age**
- **152 days**
## **Competition & brand share**
The top 5 products capture 86% of clicks — a locked-up shelf that new listings rarely crack.
**Brands**
**5 **▼falling
**Sellers**
**74**
**Top-5 brand share**
**100%**
Top 20: 100%
**Top-5 click share**
**86%**
Top 20: 100%
**Open market**
**0%**
- K-Seal64% - Bar's Leaks25% - Liqui Moly5% - Visbella4% - ACDelco2%
## **Demand & seasonality**
Weekly Amazon search volume, last 104 weeks — -12.2% search growth over the last 90 days.
6K4KSpike '25 seasonSepDecMarJunAugNovMarMay
Peak months: Aug · busiest ÷ quietest = 1.7×
[**Open Trend **](https://flapen.com/research/us/automotive/stop-leak/trend)
## **Top stop leak search terms**
- **radiator stop leak**45K/yr-2.3%11.6% conv. - **k seal**28K/yr-13.6%9.7% conv. - **coolant leak sealer**11K/yr-8.2%11.2% conv. - **k seal permanent coolant leak repair**10K/yr+18.1%16.7% conv. - **coolant stop leak**8K/yr-29.1%11.7% conv. - **bars leak**8K/yr-31.3%4.1% conv. - **radiator leak sealer**9K/yr-28.1%13.6% conv. - **radiator stop leak sealant heavy duty**7K/yr-4.5%13.8% conv. - **stop leak radiator treatment**7K/yr-32.4%13.8% conv. - **k-seal coolant leak repair**7K/yr-20.7%19.1% conv. [**All search terms **](https://flapen.com/research/us/automotive/stop-leak/search-terms)
## **Top stop leak products on Amazon**
Each bubble is one product — market share against review moat; bubble size tracks estimated sales, color grades how beatable the incumbent looks.
0%15%$43K30%$85K45%$128K60%$171K1001K10K100K Reviews — right = deep review moatMarket share (90d) ≈ est. sales
Beatable (≤4.3★) Contested Strong incumbent (>4.7★)
All 9 tracked products in this niche — three views at once, no toggling.
### **Top sellers**
by 90-day click share
[1**K-Seal ST5501 Multi-Purpose One Step Coolant Leak Repair 8oz Pour and Go Mixes with All Antifreeze No Flushing Required**K-Seal**$12.56**4.3★13,323 rev](https://www.amazon.com/dp/B001QT9KO6) [2**Bars Leaks Cooling System Radiator Stop Leak 16.9 oz.**Bar's Leaks**$7.77**4.3★3,820 rev](https://www.amazon.com/dp/B002696FA2) [3**K-Seal ST5516 Heavy-Duty Multi-Purpose One Step Coolant Leak Repair 16 oz Pour and Go Mixes with All Antifreeze No Flushing Required**K-Seal**$20.27**4.4★1,665 rev](https://www.amazon.com/dp/B002BJEG3U) [4**K-Seal ST3501 Pour & Go Head Gasket Sealer 16 oz Repairs Blown Head Gaskets Cracked Heads & Engine Blocks**K-Seal**$22.51**4.1★2,109 rev](https://www.amazon.com/dp/B00QYZIVA6) [5**Bars Leaks 1109 Liquid Copper Block Seal Intake and Radiator Stop Leak 18 oz. | One Step Safe for All Cooling Systems**Bar's Leaks**$8.07**4.3★1,506 rev](https://www.amazon.com/dp/B002PX91OG)
**~~View all top sellers →~~**
### **Newest**
by launch date
[**Visbella Radiator Stop Leak Sealer Conditioner Radiator Repair Kit Car Heater Core Freeze Plugs Cooling System & Radiator Repair (Tube pcs 1)**Visbella**$8.06**154 rev2y ago](https://www.amazon.com/dp/B0D1B7Z26G) [**Bars Leaks Radiator Stop Leak 11 oz**Bar's Leaks**$4.99**232 rev2y ago](https://www.amazon.com/dp/B0CLB9NGG3) [**Liqui Moly Radiator Stop Leak | 250 ml | Cooler additive | SKU: 20132**Liqui Moly**$12.75**655 rev8y ago](https://www.amazon.com/dp/B076ZP45Z5) [**K-Seal ST3501 Pour & Go Head Gasket Sealer 16 oz Repairs Blown Head Gaskets Cracked Heads & Engine Blocks**K-Seal**$22.51**2,109 rev11y ago](https://www.amazon.com/dp/B00QYZIVA6) [**K-Seal ST5516 Heavy-Duty Multi-Purpose One Step Coolant Leak Repair 16 oz Pour and Go Mixes with All Antifreeze No Flushing Required**K-Seal**$20.27**1,665 rev17y ago](https://www.amazon.com/dp/B002BJEG3U)
**~~View all new products →~~**
### **Trending**
90-day click momentum
[**K-Seal ST5501 Multi-Purpose One Step Coolant Leak Repair 8oz Pour and Go Mixes with All Antifreeze No Flushing Required**K-Seal**$12.56**4.3★**▲ 30%**](https://www.amazon.com/dp/B001QT9KO6) [**Liqui Moly Radiator Stop Leak | 250 ml | Cooler additive | SKU: 20132**Liqui Moly**$12.75**4.4★**— 8%**](https://www.amazon.com/dp/B076ZP45Z5) [**Bars Leaks Cooling System Radiator Stop Leak 16.9 oz.**Bar's Leaks**$7.77**4.3★**— 4%**](https://www.amazon.com/dp/B002696FA2) [**Visbella Radiator Stop Leak Sealer Conditioner Radiator Repair Kit Car Heater Core Freeze Plugs Cooling System & Radiator Repair (Tube pcs 1)**Visbella**$8.06**4.5★**— 2%**](https://www.amazon.com/dp/B0D1B7Z26G) [**K-Seal ST5516 Heavy-Duty Multi-Purpose One Step Coolant Leak Repair 16 oz Pour and Go Mixes with All Antifreeze No Flushing Required**K-Seal**$20.27**4.4★**▼ 11%**](https://www.amazon.com/dp/B002BJEG3U)
**~~View all trending →~~**
## **What buyers say about stop leak**
What buyers praise and complain about, mined from review topics.
### **What buyers love **
**Leak-Proof**26%
*“Stop leak”*
**Efficiency**15%
*“Works well”*
**Value For Money**11%
*“Worth the purchase”*
**Quality-Overall**11%
*“quality are all good”*
**Advertised Vs Actual Product**7%
*“Works as advertised”*
**Coolant**5%
*“Stopped my coolant leak”*
**Ease Of Use**3%
*“Easy peasy”*
**Instructions/User Manual/Troubleshooting**3%
*“Followed the directions”*
**Maintenance And Repair**2%
*“that it would not affect the repair”*
**Durability**2%
*“its still holding”*
### **What buyers complain about **
**Leak-Proof**32%
*“Had a leak”*
**Functionality-Overall**16%
*“Did not work”*
**Coolant**9%
*“If you have a slight loss of coolant or a head gasket that is just starting to leak”*
**Maintenance And Repair**5%
*“Repairs are ridiculous”*
**Heating**4%
*“Car started overheating again”*
**Jamming/Clogging**3%
*“clogs”*
**Instructions/User Manual/Troubleshooting**3%
*“Lasted exactly 7 miles when followed directions exactly ending in large fail”*
**Value For Money**2%
*“which is expensive ($4500 quoted for my last car).”*
**Quality-Overall**2%
*“Trash”*
**Durability**2%
*“Does not last”*
### **Top return reasons **
**Leak-Proof**20%
**Coolant**19%
**Functionality-Overall**16%
**Compatibility-Overall**10%
**Maintenance And Repair**7%
**Defective Material/Parts**6%
**Value For Money**6%
**Advertised Vs Actual Product**5%
**Product Condition**3%
**Size-Overall**2%
## **Common questions**
- **Is stop leak profitable to sell on Amazon United States?**
- The niche generates $284K/yr across 9 tracked products. 90-day search growth is -12.2%. Flapen's verdict: Skip it (43/100).
- **How competitive is the stop leak niche?**
- 5 brands and 74 sellers compete. The top 5 products take 86% of clicks and top 5 brands hold 100% of demand.
- **What do buyers complain about in stop leak?**
- Top complaints mined from reviews: Leak-Proof, Functionality-Overall, Coolant. The return rate is 1.5%.
- **When does demand for stop leak peak?**
- Demand peaks in Aug; the busiest month runs 1.7× the quietest.
- **What does it cost to enter the stop leak niche?**
- Listings span $4.10–$22.51; the average listing price is $11.23 (sweet spot $15–$100). The average incumbent carries 2,752 reviews — the moat a new listing must climb.
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