---
title: "Rear Main Seal — $200K/yr Amazon US Niche (2026) - Flapen"
canonical_url: "https://flapen.com/research/us/automotive/rear-main-seal"
last_updated: "2026-08-10T00:13:37.139Z"
locale: en
meta:
description: "Niche score 51/100 · $200K/yr market · 258K searches/yr · $19.46 avg price. Soft demand (-15.5% this quarter) keeps it on the watch list. Data updated Jul 2026."
"og:description": "Niche score 51/100 · $200K/yr market · 258K searches/yr · $19.46 avg price. Soft demand (-15.5% this quarter) keeps it on the watch list. Data updated Jul 2026."
"og:title": "Rear Main Seal — $200K/yr Amazon US Niche (2026) - Flapen"
---
# **rear main seal**
**Worth a look**
Shows a thin review moat (227 avg reviews), but soft demand (-15.5% this quarter) keeps it on the watch list.
Market size 39Growth 17Conversion 50Competition 79Returns 44Price range 84Avg price 86Brand share 38Review moat 89Quality gap 40
**Review moat**
**Great****227.43**
avg incumbent reviews — the moat a new listing must climb
**Avg price**
**Great****$19.46**
avg listing price — sweet spot $15–$100
**Price range**
**Great****$6.68–$69.20**
cheapest to priciest tracked listing — scored on the share inside $15–$100
**Competition**
**Great****36%**
top-5 click share — an open shelf
**Conversion**
**Good****4.0%**
search→purchase rate — share of searches ending in a sale
**Returns**
**Okay****3.5%**
return rate — above 5% kills the launch gate
**Quality gap**
**Okay****4.5★**
avg incumbent rating — lower means beatable quality
**Market size**
**Okay****$200K**
$200K/yr · 258K searches
**Brand share**
**Okay****82%**
top-5 brand share — brands hold most of the demand
**Growth**
**Bad****-15.5%**
90-day search growth — must beat 0% to launch
According to Flapen's Amazon United States niche tracking, rear main seal is a $200K/yr Amazon United States market (258K searches/yr). The top 5 brands hold 82% of demand. Demand peaks in Mar. Verdict: Worth a look — 51/100.
Data updated Jul 9, 2026 · scored weekly · [~~How we score niches ~~](https://flapen.com/research/methodology)
## **rear main seal market data**
- **Units sold / yr**
- **10K–13K**
- avg 100–250/product
- **Revenue / yr**
- **$195K–$243K**
- units × avg price
- **Conversion rate**
- **4.0%**
- **Avg BSR**
- **#548**
- **Page quality**
- **0%**
- **Prime**
- **100%**
- **Sponsored**
- **95%**
- **Out of stock**
- **0.0%**
- **Avg brand age**
- **59 months**
- **Avg seller age**
- **152 days**
## **Competition & brand share**
Clicks spread well past the top 5 (36% combined) — an open shelf where new products get seen.
**Brands**
**17 **▲rising
**Sellers**
**113**
**Top-5 brand share**
**82%**
Top 20: 100%
**Top-5 click share**
**36%**
Top 20: 66%
**Open market**
**12%**
- Fel-Pro47% - Dorman14% - ACDelco9% - National6% - A-Premium6% - GM GENUINE PARTS6% - Open — no brand owns it (11 brands, 12%)
## **Demand & seasonality**
Weekly Amazon search volume, last 104 weeks — -15.5% search growth over the last 90 days.
6K4KSpike '25Spike '26 seasonSepDecMarJunAugNovMarMay
Peak months: Mar · busiest ÷ quietest = 1.6×
[**Open Trend **](https://flapen.com/research/us/automotive/rear-main-seal/trend)
## **Top rear main seal search terms**
- **rear main seal**135K/yr-14.3%2.3% conv. - **crankshaft seal**49K/yr-16.9%1.8% conv. - **front crankshaft seal**19K/yr-20.7%1.5% conv. - **front main seal**16K/yr-14.6%2.0% conv. - **rear main seal kit**19K/yr-21.6%2.3% conv. - **crank seal**10K/yr-8.7%2.4% conv. - **crank shaft seal**5K/yr+9.1%1.3% conv. - **rear crankshaft seal**5K/yr-27.0%1.3% conv. [**All search terms **](https://flapen.com/research/us/automotive/rear-main-seal/search-terms)
## **Top rear main seal 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%4%$8K8%$16K12%$24K16%$32K101001K10K 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 635-518 Engine Rear Main Seal Cover Compatible with Select Models**Dorman**$49.63**4.6★1,169 rev](https://www.amazon.com/dp/B009ZBSBMO) [2**FEL-PRO BS 40640 Engine Crankshaft Seal Kit for Chevrolet Silverado 1500**Fel-Pro**$21.59**4.8★2,112 rev](https://www.amazon.com/dp/B000C2GA1Y) [3![A-Premium Engine Rear Main Seal Cover Kit [OHV 8Cyl 4.8 5.3 5.7 6.0 6.2 7.0L] Compatible with Chevy GMC Cadillac Hummer Isuzu Pontiac Saab & Buick fits Express Silverado Sierra & More Models](https://m.media-amazon.com/images/I/41gRkRB2CrL.jpg)**A-Premium Engine Rear Main Seal Cover Kit \[OHV 8Cyl 4.8 5.3 5.7 6.0 6.2 7.0L\] Compatible with Chevy GMC Cadillac Hummer Isuzu Pontiac Saab & Buick fits Express Silverado Sierra & More Models**A-Premium**$36.37**4.1★349 rev](https://www.amazon.com/dp/B082X9HMHG) [4**FEL-PRO TCS 46117 Engine Crankshaft Seal Kit for Ford F-150**Fel-Pro**$8.37**4.7★495 rev](https://www.amazon.com/dp/B002LWQ1MQ) [5**FEL-PRO TCS 46051 Engine Crankshaft Seal Kit for Honda CR-V**Fel-Pro**$8.34**4.7★535 rev](https://www.amazon.com/dp/B000Q0R598)
**~~View all top sellers →~~**
### **Newest**
by launch date
[**Engine Rear Main Seal Cover Kit with Gasket & Bolt Compatible with Cadillac Escalade GMC Yukon Sierra Chevy Suburban Silverado Tahoe Express 4.8 5.3 6.0 6.2L Replace# 635-518 12633579 12639250**AUTOBABA**$36.04**123 rev2y ago](https://www.amazon.com/dp/B0CZLBB9GP) [**National 711024 Engine Crankshaft Seal**National**$11.34**51 rev2y ago](https://www.amazon.com/dp/B0CFW1W1HW) [**RADHLBNIU Rear Main Seal Kit Compatible with Chevy Tahoe Suburban Silverado Express Avalanche Cadillac Escalade GMC Yukon Sierra Savana 4.8L 5.3L 6.0L 6.2L Replaces# 635-518 12633579 12639250**RADHLBNIU**$36.39**92 rev3y ago](https://www.amazon.com/dp/B0BYLWZTMR) [![A-Premium Engine Rear Main Seal Cover Kit [OHV 8Cyl 4.8 5.3 5.7 6.0 6.2 7.0L] Compatible with Chevy GMC Cadillac Hummer Isuzu Pontiac Saab & Buick fits Express Silverado Sierra & More Models](https://m.media-amazon.com/images/I/41gRkRB2CrL.jpg)**A-Premium Engine Rear Main Seal Cover Kit \[OHV 8Cyl 4.8 5.3 5.7 6.0 6.2 7.0L\] Compatible with Chevy GMC Cadillac Hummer Isuzu Pontiac Saab & Buick fits Express Silverado Sierra & More Models**A-Premium**$36.37**349 rev6y ago](https://www.amazon.com/dp/B082X9HMHG) [**GM Genuine Parts 89060436 Crankshaft Rear Main Seal**GM GENUINE PARTS**$27.16**183 rev7y ago](https://www.amazon.com/dp/B07FZFVXL6)
**~~View all new products →~~**
### **Trending**
90-day click momentum
[**National 100470 Engine Crankshaft Seal for Chevrolet Silverado 1500**National**$10.57**4.9★**▲ 82%**](https://www.amazon.com/dp/B001KR7AJQ) [**FEL-PRO BS 40619 Rear Main Seal Set**Fel-Pro**$19.68**4.4★**▲ 70%**](https://www.amazon.com/dp/B000CNH170) [**RADHLBNIU Rear Main Seal Kit Compatible with Chevy Tahoe Suburban Silverado Express Avalanche Cadillac Escalade GMC Yukon Sierra Savana 4.8L 5.3L 6.0L 6.2L Replaces# 635-518 12633579 12639250**RADHLBNIU**$36.39**4.6★**▲ 64%**](https://www.amazon.com/dp/B0BYLWZTMR) [**FEL-PRO BS 40666 Rear Main Seal Set**Fel-Pro**$11.16**4.7★**▲ 63%**](https://www.amazon.com/dp/B000CNKXYS) [**GM Genuine Parts 296-02 (12585673) Engine Front Cover Seal**GM GENUINE PARTS**$23.61**4.8★**▲ 15%**](https://www.amazon.com/dp/B000C9MBX8)
**~~View all trending →~~**
## **What buyers say about rear main seal**
What buyers praise and complain about, mined from review topics.
### **What buyers love **
**Size-Overall**36%
*“Fit perfect”*
**Quality-Overall**22%
*“Excellent product”*
**Leak-Proof**16%
*“Not leaking”*
**Advertised Vs Actual Product**10%
*“Works as it should”*
**Value For Money**4%
*“Good purchase for the price”*
**Assembly/Installation**4%
*“Easy install”*
**Efficiency**4%
*“Works great”*
**Safety Standards**1%
*“Seals the rear main as it should”*
**Amplification**0%
*“Best 4.0 RMS out there”*
**Ease Of Use**0%
*“Easier to guide and push in”*
### **What buyers complain about **
**Leak-Proof**38%
*“Leaking”*
**Compatibility-Overall**24%
*“Doesn't work for d16y7 or d16y8”*
**Size-Overall**11%
*“ID is slightly smaller”*
**Quality-Overall**7%
*“Junk”*
**Durability**6%
*“Lasted 6 months and blew out”*
**Defective Material/Parts**5%
*“Received unusable part”*
**Thickness**2%
*“This is actually thicker than the factory cover”*
**Maintenance And Repair**1%
*“I replaced it before setting the engine in the new frame to save myself the headache of having to replace it later”*
**Lubrication**1%
*“I lost oil pressure late January 2026”*
### **Top return reasons **
**Size-Overall**40%
**Leak-Proof**9%
**Compatibility-Overall**9%
**Defective Material/Parts**8%
**Value For Money**8%
**Advertised Vs Actual Product**7%
**Product Condition**3%
**Quality-Overall**3%
**Maintenance And Repair**2%
**Assembly/Installation**2%
## **Common questions**
- **Is rear main seal profitable to sell on Amazon United States?**
- The niche generates $200K/yr across 58 tracked products. 2 of 2 products launched in the last 360 days are still selling. 90-day search growth is -15.5%. Flapen's verdict: Worth a look (51/100).
- **How competitive is the rear main seal niche?**
- 17 brands and 113 sellers compete. The top 5 products take 36% of clicks and top 5 brands hold 82% of demand.
- **What do buyers complain about in rear main seal?**
- Top complaints mined from reviews: Leak-Proof, Compatibility-Overall, Size-Overall. The return rate is 3.5%.
- **When does demand for rear main seal peak?**
- Demand peaks in Mar; the busiest month runs 1.6× the quietest.
- **What does it cost to enter the rear main seal niche?**
- Listings span $6.68–$69.20; the average listing price is $19.46 (sweet spot $15–$100). The average incumbent carries 227 reviews — the moat a new listing must climb.
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