---
title: "Coolant Reservoir Cap — $73K/yr Amazon US Niche (2026) - Flapen"
canonical_url: "https://flapen.com/research/us/automotive/coolant-reservoir-cap"
last_updated: "2026-08-10T18:15:05.382Z"
locale: en
meta:
description: "Niche score 55/100 · $73K/yr market · 162K searches/yr · $8.59 avg price. A small market ($73K/yr) keeps it on the watch list. Data updated Jul 2026."
"og:description": "Niche score 55/100 · $73K/yr market · 162K searches/yr · $8.59 avg price. A small market ($73K/yr) keeps it on the watch list. Data updated Jul 2026."
"og:title": "Coolant Reservoir Cap — $73K/yr Amazon US Niche (2026) - Flapen"
---
# **coolant reservoir cap**
**Worth a look**
Shows no brand lock-in (top 5 brands take 35% of clicks), but a small market ($73K/yr) keeps it on the watch list.
Market size 18Growth 20Conversion 61Competition 93Returns 55Price range 31Avg price 24Brand share 96Review moat 87Quality gap 76
**Brand share**
**Incredible****35%**
top-5 brand share — no brand owns this niche
**Competition**
**Great****22%**
top-5 click share — an open shelf
**Review moat**
**Great****264.25**
avg incumbent reviews — the moat a new listing must climb
**Quality gap**
**Great****4.3★**
avg incumbent rating — lower means beatable quality
**Conversion**
**Good****5.3%**
search→purchase rate — share of searches ending in a sale
**Returns**
**Good****2.8%**
return rate — above 5% kills the launch gate
**Price range**
**Okay****$3.08–$20.38**
cheapest to priciest tracked listing — scored on the share inside $15–$100
**Avg price**
**Bad****$8.59**
avg listing price — sweet spot $15–$100
**Growth**
**Bad****-10.1%**
90-day search growth — must beat 0% to launch
**Market size**
**Bad****$73K**
$73K/yr · 162K searches
**Signals**[** No Dominant Brand**](https://flapen.com/research/niches?market=us&signal=no_dominant_brand "Top brand's click share < 20%")
According to Flapen's Amazon United States niche tracking, coolant reservoir cap is a $73K/yr Amazon United States market (162K searches/yr). The top 5 brands hold 35% of demand. Verdict: Worth a look — 55/100.
Data updated Jul 9, 2026 · scored weekly · [~~How we score niches ~~](https://flapen.com/research/methodology)
## **coolant reservoir cap market data**
- **Units sold / yr**
- **10K–13K**
- avg 100–250/product
- **Revenue / yr**
- **$86K–$107K**
- units × avg price
- **Conversion rate**
- **5.3%**
- **Avg BSR**
- **#2,353**
- **Page quality**
- **0%**
- **Prime**
- **100%**
- **Sponsored**
- **56%**
- **Out of stock**
- **0.8%**
- **Avg brand age**
- **32 months**
- **Avg seller age**
- **160 days**
## **Competition & brand share**
Clicks spread well past the top 5 (22% combined) — an open shelf where new products get seen.
**Brands**
**61 **▲rising
**Sellers**
**148**
**Top-5 brand share**
**35%**
Top 20: 74%
**Top-5 click share**
**22%**
Top 20: 57%
**Open market**
**61%**
- Dorman13% - ACDelco7% - ROVIKE5% - KEVWR5% - SWQS4% - DeFageH4%
## **Demand & seasonality**
Weekly Amazon search volume, last 104 weeks — -10.1% search growth over the last 90 days.
4K3KHoliday '24 seasonSepDecMarJunAugNovMarMay
No pronounced peak months · busiest ÷ quietest = 1.1×
[**Open Trend **](https://flapen.com/research/us/automotive/coolant-reservoir-cap/trend)
## **Top coolant reservoir cap search terms**
- **coolant reservoir cap**68K/yr-7.0%4.6% conv. - **coolant cap**30K/yr-17.3%4.5% conv. - **coolant cap replacement**11K/yr-12.0%5.1% conv. - **coolant reservoir tank cap**12K/yr-1.9%5.0% conv. - **reservoir cap**10K/yr-15.2%2.7% conv. - **radiator reservoir cap**8K/yr-20.7%5.9% conv. - **coolant overflow cap**5K/yr+32.0%4.0% conv. - **radiator overflow cap**4K/yr+10.4%4.7% conv. - **engine coolant reservoir cap**4K/yr-2.9%4.7% conv. - **coolant tank cap**4K/yr-7.2%4.3% conv. [**All search terms **](https://flapen.com/research/us/automotive/coolant-reservoir-cap/search-terms)
## **Top coolant reservoir 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.
0%2%$1K4%$3K6%$4K8%$6K1101001K10K Reviews — right = deep review moatMarket share (90d) ≈ est. sales
Beatable (≤4.3★) Contested Strong incumbent (>4.7★)
All 24 tracked products in this niche — three views at once, no toggling.
### **Top sellers**
by 90-day click share
[1**Dorman 54201 Engine Coolant Reservoir Cap Compatible with Select Models**Dorman**$12.42**4.6★4,822 rev](https://www.amazon.com/dp/B00Z7MMSIS) [2**2PCS Engine Radiator Coolant Water Tank Black Reservoir Cap Compatible with Infiniti Nissan Renault OEM# 21712-79900**KEVWR**$6.26**4.4★385 rev](https://www.amazon.com/dp/B0CH2WHK8Q) [3**DeFageH 2Pcs Coolant Reservoir Cap - Premium Leak-Proof Coolant Caps for OEM# 21712-79900 Compatible with Nissan Pathfinder Maxima Murano Infiniti G35**DeFageH**$4.37**4.6★26 rev](https://www.amazon.com/dp/B0GHXR6BNP) [4**13502353 Coolant Reservoir Cap for Chevy GMC Buick Cadillac -Silverado 1500 2500 3500 Express Avalanche Suburban Captiva Cavalier Equinox Malibu Savana Sierra Yukon Radiator Surge Tank Cap**ROVIKE**$11.52**4.4★162 rev](https://www.amazon.com/dp/B09XWDBMN9) [5**Car Radiator Cap Replacement OEM#68442532aa 53479332 Coolant Reservoir Cap Compatible with Chrysler Dodge Jeep Ram Standard Car Accessories Radiator Cover Easy to Mounting**Stacool**$7.20**4.5★84 rev](https://www.amazon.com/dp/B0D14C7WT3)
**~~View all top sellers →~~**
### **Newest**
by launch date
[**4PCS Coolant Reservoir Cap Replacement OEM# 21712-79900 - Radiator Overflow Coolant Reservoir Tank Cap Compatible with Nissan Murano Rogue Versa Quest & Infiniti EX35 FX37 G35 M35**Alfaly**$3.08**11 rev4mo ago](https://www.amazon.com/dp/B0GQV5L763) [**DeFageH 2Pcs Coolant Reservoir Cap - Premium Leak-Proof Coolant Caps for OEM# 21712-79900 Compatible with Nissan Pathfinder Maxima Murano Infiniti G35**DeFageH**$4.37**26 rev5mo ago](https://www.amazon.com/dp/B0GHXR6BNP) [**Houlishu 2 Pack Coolant Reservoir Cap Replacement Universal Radiator Reservoir Cap Compatible with OEM# 21712-79900 Black Overflow Tank Cover for Water & Antifreeze**houlishu**$6.09**18 rev5mo ago](https://www.amazon.com/dp/B0GGYJHFBD) [**SWQS Coolant Reservoir Tank Cap for Toyota Engine Coolant Expansion Tank Cap 16471-0A030 Radiator Coolant Caps Replacement for Toyota Sienna 2004-2010 Lexus RX330 2004-2006 & RX350 2007-2009 (Black)**SWQS**$9.93**2 rev7mo ago](https://www.amazon.com/dp/B0G4TXK4LH) [**HZEL Car Coolant Reservoir Cap Vehicle Radiator Surge Tank Cap OEM# 13502353 13598760 1305248 Automotive Replacement Accessories Compatibility with Encore Regal Verano**HZEL**$5.78**16 rev10mo ago](https://www.amazon.com/dp/B0FPWXW23X)
**~~View all new products →~~**
### **Trending**
90-day click momentum
[**4PCS Coolant Reservoir Cap Replacement OEM# 21712-79900 - Radiator Overflow Coolant Reservoir Tank Cap Compatible with Nissan Murano Rogue Versa Quest & Infiniti EX35 FX37 G35 M35**Alfaly**$3.08**4.8★**▲ 302%**](https://www.amazon.com/dp/B0GQV5L763) [**Houlishu 2 Pack Coolant Reservoir Cap Replacement Universal Radiator Reservoir Cap Compatible with OEM# 21712-79900 Black Overflow Tank Cover for Water & Antifreeze**houlishu**$6.09**3.4★**▲ 259%**](https://www.amazon.com/dp/B0GGYJHFBD) [**DeFageH 2Pcs Coolant Reservoir Cap - Premium Leak-Proof Coolant Caps for OEM# 21712-79900 Compatible with Nissan Pathfinder Maxima Murano Infiniti G35**DeFageH**$4.37**4.6★**▲ 216%**](https://www.amazon.com/dp/B0GHXR6BNP) [**SWQS Coolant Reservoir Tank Cap for Toyota Engine Coolant Expansion Tank Cap 16471-0A030 Radiator Coolant Caps Replacement for Toyota Sienna 2004-2010 Lexus RX330 2004-2006 & RX350 2007-2009 (Black)**SWQS**$9.93**3.0★**▲ 184%**](https://www.amazon.com/dp/B0G4TXK4LH) [**HZEL Car Coolant Reservoir Cap Vehicle Radiator Surge Tank Cap OEM# 13502353 13598760 1305248 Automotive Replacement Accessories Compatibility with Encore Regal Verano**HZEL**$5.78**3.8★**▲ 124%**](https://www.amazon.com/dp/B0FPWXW23X)
**~~View all trending →~~**
## **What buyers say about coolant reservoir cap**
What buyers praise and complain about, mined from review topics.
### **What buyers love **
**Size-Overall**55%
*“Fit great”*
**Quality-Overall**13%
*“Quality replacement”*
**Value For Money**7%
*“Good price”*
**Advertised Vs Actual Product**5%
*“Worked as advertised”*
**Coolant**4%
*“Worked great as direct replacement for coolant reserve tank fill cap”*
**Efficiency**4%
*“Does the job just fine”*
**Leak-Proof**2%
*“No leaks so far”*
**Assembly/Installation**1%
*“Easy installation”*
**Durability**1%
*“durable”*
**Ease Of Use**1%
*“Easy to use”*
### **What buyers complain about **
**Size-Overall**23%
*“Doesnt fit advertised to fit”*
**Compatibility-Overall**14%
*“Did not fit Suzuki Kizashi”*
**Quality-Overall**11%
*“Expected much higher quality from Gates”*
**Durability**8%
*“Not durable”*
**Coolant**7%
*“Stop coolant loss”*
**Functionality-Overall**5%
*“doesnt fix”*
**Leak-Proof**4%
*“Will leak everywhere”*
**Advertised Vs Actual Product**3%
*“Do not believe what is advertised”*
**Value For Money**3%
*“absolute waste of money”*
**Pressure**3%
*“It doesnt hold pressure”*
### **Top return reasons **
**Size-Overall**53%
**Coolant**22%
**Compatibility-Overall**10%
**Advertised Vs Actual Product**3%
**Defective Material/Parts**3%
**Pressure**2%
**Value For Money**2%
**Functionality-Overall**1%
**Leak-Proof**1%
**Product Condition**1%
## **Common questions**
- **Is coolant reservoir cap profitable to sell on Amazon United States?**
- The niche generates $73K/yr across 89 tracked products. 0 of 15 products launched in the last 360 days are still selling. 90-day search growth is -10.1%. Flapen's verdict: Worth a look (55/100).
- **How competitive is the coolant reservoir cap niche?**
- 61 brands and 148 sellers compete. The top 5 products take 22% of clicks and top 5 brands hold 35% of demand.
- **What do buyers complain about in coolant reservoir cap?**
- Top complaints mined from reviews: Size-Overall, Compatibility-Overall, Quality-Overall. The return rate is 2.8%.
- **When does demand for coolant reservoir cap peak?**
- Demand is steady year-round — the busiest month runs 1.1× the quietest.
- **What does it cost to enter the coolant reservoir cap niche?**
- Listings span $3.08–$20.38; the average listing price is $8.59 (sweet spot $15–$100). The average incumbent carries 264 reviews — the moat a new listing must climb.
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