stop leak
Skip itBrand-locked demand (top 5 brands take 100% of clicks) — this niche doesn't clear our bar today.
Conversion
Incredible13.6%search→purchase rate — share of searches ending in a sale
Returns
Great1.5%return rate — above 5% kills the launch gate
Quality gap
Good4.4★avg incumbent rating — lower means beatable quality
Market size
Good$284K$284K/yr · 187K searches
Avg price
Okay$11.23avg listing price — sweet spot $15–$100
Price range
Okay$4.10–$22.51cheapest to priciest tracked listing — scored on the share inside $15–$100
Review moat
Okay2,752.11avg incumbent reviews — the moat a new listing must climb
Growth
Bad-12.2%90-day search growth — must beat 0% to launch
Competition
Bad86%top-5 click share — a locked-up shelf
Brand share
Bad100%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
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.Peak months: Aug · busiest ÷ quietest = 1.7×
Top stop leak search terms
- radiator stop leak45K/yr
- k seal28K/yr
- coolant leak sealer11K/yr
- k seal permanent coolant leak repair10K/yr
- coolant stop leak8K/yr
- bars leak8K/yr
- radiator leak sealer9K/yr
- radiator stop leak sealant heavy duty7K/yr
- stop leak radiator treatment7K/yr
- k-seal coolant leak repair7K/yr
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.
All 9 tracked products in this niche — three views at once, no toggling.
Top sellers
by 90-day click share
K-Seal ST5501 Multi-Purpose One Step Coolant Leak Repair 8oz Pour and Go Mixes with All Antifreeze No Flushing Required
K-Seal$12.564.3★13,323 rev
Bars Leaks Cooling System Radiator Stop Leak 16.9 oz.
Bar's Leaks$7.774.3★3,820 rev
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$20.274.4★1,665 rev
K-Seal ST3501 Pour & Go Head Gasket Sealer 16 oz Repairs Blown Head Gaskets Cracked Heads & Engine Blocks
K-Seal$22.514.1★2,109 rev
Bars Leaks 1109 Liquid Copper Block Seal Intake and Radiator Stop Leak 18 oz. | One Step Safe for All Cooling Systems
Bar's Leaks$8.074.3★1,506 rev
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$8.06154 rev
Bars Leaks Radiator Stop Leak 11 oz
Bar's Leaks$4.99232 rev
Liqui Moly Radiator Stop Leak | 250 ml | Cooler additive | SKU: 20132
Liqui Moly$12.75655 rev
K-Seal ST3501 Pour & Go Head Gasket Sealer 16 oz Repairs Blown Head Gaskets Cracked Heads & Engine Blocks
K-Seal$22.512,109 rev
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$20.271,665 rev
Trending
90-day click momentumK-Seal ST5501 Multi-Purpose One Step Coolant Leak Repair 8oz Pour and Go Mixes with All Antifreeze No Flushing Required
K-Seal$12.564.3★
Liqui Moly Radiator Stop Leak | 250 ml | Cooler additive | SKU: 20132
Liqui Moly$12.754.4★
Bars Leaks Cooling System Radiator Stop Leak 16.9 oz.
Bar's Leaks$7.774.3★
Visbella Radiator Stop Leak Sealer Conditioner Radiator Repair Kit Car Heater Core Freeze Plugs Cooling System & Radiator Repair (Tube pcs 1)
Visbella$8.064.5★
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$20.274.4★
What buyers say about stop leak
What buyers praise and complain about, mined from review topics.What buyers love
“Stop leak”
“Works well”
“Worth the purchase”
“quality are all good”
“Works as advertised”
“Stopped my coolant leak”
“Easy peasy”
“Followed the directions”
“that it would not affect the repair”
“its still holding”
What buyers complain about
“Had a leak”
“Did not work”
“If you have a slight loss of coolant or a head gasket that is just starting to leak”
“Repairs are ridiculous”
“Car started overheating again”
“clogs”
“Lasted exactly 7 miles when followed directions exactly ending in large fail”
“which is expensive ($4500 quoted for my last car).”
“Trash”
“Does not last”
Top return reasons
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.