radiator cap
Worth a lookShows a fragmented shelf (top 5 take 23% of clicks), but a failed launch gate (market size, growth, or returns) keeps it on the watch list.
Competition
Great23%top-5 click share — an open shelf
Review moat
Great309.48avg incumbent reviews — the moat a new listing must climb
Quality gap
Great4.3★avg incumbent rating — lower means beatable quality
Brand share
Good62%top-5 brand share — brands hold most of the demand
Conversion
Good5.6%search→purchase rate — share of searches ending in a sale
Returns
Good2.9%return rate — above 5% kills the launch gate
Market size
Okay$244K$244K/yr · 422K searches
Price range
Okay$5.07–$23.15cheapest to priciest tracked listing — scored on the share inside $15–$100
Avg price
Okay$10.26avg listing price — sweet spot $15–$100
Growth
Bad-6.4%90-day search growth — must beat 0% to launch
According to Flapen's Amazon United States niche tracking, radiator cap is a $244K/yr Amazon United States market (422K searches/yr). The top 5 brands hold 62% of demand. Verdict: Worth a look — 59/100.
Data updated Jul 9, 2026 · scored weekly · How we score niches
radiator cap market data
- Units sold / yr
- 25K–30K
- avg 250–500/product
- Revenue / yr
- $257K–$308K
- units × avg price
- Conversion rate
- 5.6%
- Avg BSR
- #1,197
- Page quality
- 0%
- Prime
- 100%
- Sponsored
- 58%
- Out of stock
- 1.5%
- Avg brand age
- 48 months
- Avg seller age
- 160 days
Competition & brand share
Clicks spread well past the top 5 (23% combined) — an open shelf where new products get seen.Brands
37 falling
Sellers
170
Top-5 brand share
62%
Top 20: 91%
Top-5 click share
23%
Top 20: 55%
Open market
34%
- Gates23%
- MotoRad15%
- ACDelco10%
- Manymiba9%
- RBOKO5%
- IHOTDER5%
Demand & seasonality
Weekly Amazon search volume, last 104 weeks — -6.4% search growth over the last 90 days.No pronounced peak months · busiest ÷ quietest = 1.2×
Top radiator cap search terms
- radiator cap342K/yr
- radiator cap replacement33K/yr
- tapn de radiador8K/yr
- radiator cap 16 psi5K/yr
- oem radiator cap5K/yr
- stant radiator cap5K/yr
- automotive replacement radiator standard5K/yr
- tapa de radiador6K/yr
- radiator cap oem10K/yr
- radiator caps3K/yr
Top radiator cap 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 24 tracked products in this niche — three views at once, no toggling.
Top sellers
by 90-day click share
Gates 31528 Standard Radiator Cap
Gates$8.474.6★683 rev
ACDelco GM Original Equipment RC27 (10409635) Radiator Fill Cap
ACDelco$10.724.7★1,950 rev
Gates 31336 Radiator Cap
Gates$12.484.4★851 rev
Car Radiator Cap Coolant Reservoir Cap OEM#16401-31520 1640131520 Standard Radiator Coolant Reservoir Tank Cap Compatible with Lexus Toyota Scion Auto Replacement Parts(for Lexus)
IHOTDER$5.964.6★152 rev
Teybouk High Pressure Radiator Cap Cover 1.8 bar Vehicle Radiator Cap Temperature Gauge 1.85 x 2.55 Water Tank Sealing Cover Universal for Suzuki Yamaha Motorcycle ATV Models (Black)
Teybouk$10.043.2★27 rev
Newest
by launch date
Eponcia Radiator Cover 16 PSI Engine Reservoir Cap Stainless Steel Leak-Proof Seal Cover for Radiators Dual-Lug Tank Lid Valve Cap Replacement Universal for Most Cars Fits for Dodge Jeep (Silver)
Eponcia$5.8918 rev
Teybouk High Pressure Radiator Cap Cover 1.8 bar Vehicle Radiator Cap Temperature Gauge 1.85 x 2.55 Water Tank Sealing Cover Universal for Suzuki Yamaha Motorcycle ATV Models (Black)
Teybouk$10.0427 rev
Radiator Cap for Honda Acura 1992-2005 Civic 1994-2006 Accord 1997-2005 CR-V 1995-2007 Odyssey 2003-2008 Pilot 2001-2006 MDX 1995-2005 TL 1993-1997 Civic del Sol 19045-PAA-A01 19045PAAA01
Manymiba$9.8222 rev
Radiator Cap for Jeep Dodge Chrysler 2007-2017 Patriot 2009-2018 Journey 2007-2017 Compass 2008-2012 Avenger 2007-2012 Caliber 52028810AL 52029195AK 55116901AA
Manymiba$10.1331 rev
RC27 Radiator Cap for Chevrolet Buick GMC Pontiac 1995-2002 Silverado 1991-1996 Corvette 1985-1992 Camaro 1985-1994 S10 Blazer 1992-1996 Yukon 1985-1993 Jimmy 2001 Aztek 10409635
Manymiba$9.7510 rev
Trending
90-day click momentum
MotoRad T208 Racing Radiator cap
MotoRad$9.584.3★
Radiator Cap for Honda Acura 1992-2005 Civic 1994-2006 Accord 1997-2005 CR-V 1995-2007 Odyssey 2003-2008 Pilot 2001-2006 MDX 1995-2005 TL 1993-1997 Civic del Sol 19045-PAA-A01 19045PAAA01
Manymiba$9.824.8★
Eponcia Radiator Cover 16 PSI Engine Reservoir Cap Stainless Steel Leak-Proof Seal Cover for Radiators Dual-Lug Tank Lid Valve Cap Replacement Universal for Most Cars Fits for Dodge Jeep (Silver)
Eponcia$5.893.8★
Radiator Cap for Toyota Scion Lexus 2001-2019 Highlander 2009-2017 Tacoma 2007-2020 Tundra 2007-2017 RX350 2010-2022 RX450h 2007-2016 Sienna 1640131520 1640131480 1640146610
Manymiba$9.704.5★
RC27 Radiator Cap for Chevrolet Buick GMC Pontiac 1995-2002 Silverado 1991-1996 Corvette 1985-1992 Camaro 1985-1994 S10 Blazer 1992-1996 Yukon 1985-1993 Jimmy 2001 Aztek 10409635
Manymiba$9.754.8★
What buyers say about radiator cap
What buyers praise and complain about, mined from review topics.What buyers love
“Direct fit”
“The build quality feels solid”
“Worth it”
“Just as advertised”
“No leaks after installation”
“Works as intended”
“Holds pressure well”
“Works perfectly, solved my coolant odor problem”
“Easy installation”
“Well built cap”
What buyers complain about
“Didn't fit”
“Does not fit the v6 engine”
“will start to leak”
“Bad quality”
“cause all my coolant to spill out”
“False info”
“Truck overheated”
“the bar pressure is to high”
“Dose not work”
“Failed in 3 months”
Top return reasons
Common questions
- Is radiator cap profitable to sell on Amazon United States?
- The niche generates $244K/yr across 92 tracked products. 1 of 22 products launched in the last 360 days are still selling. 90-day search growth is -6.4%. Flapen's verdict: Worth a look (59/100).
- How competitive is the radiator cap niche?
- 37 brands and 170 sellers compete. The top 5 products take 23% of clicks and top 5 brands hold 62% of demand.
- What do buyers complain about in radiator cap?
- Top complaints mined from reviews: Size-Overall, Compatibility-Overall, Leak-Proof. The return rate is 2.9%.
- When does demand for radiator cap peak?
- Demand is steady year-round — the busiest month runs 1.2× the quietest.
- What does it cost to enter the radiator cap niche?
- Listings span $5.07–$23.15; the average listing price is $10.26 (sweet spot $15–$100). The average incumbent carries 309 reviews — the moat a new listing must climb.