--- title: "rear main seal — Niche Verdict: Worth a look (55/100) | Amazon United States - Flapen" canonical_url: "https://flapen.com/amazon/research/us/automotive/rear-main-seal" last_updated: "2026-07-10T04:34:23.661Z" locale: en meta: description: "rear main seal shows demand growing +269.8%, but a small market ($200K/yr) keeps it on the watch list." "og:description": "rear main seal shows demand growing +269.8%, but a small market ($200K/yr) keeps it on the watch list." "og:title": "rear main seal — Niche Verdict: Worth a look (55/100) | Amazon United States - Flapen" --- Back to Flapen home # **rear main seal** **Worth a look****55/100 ** rear main seal shows demand growing +269.8%, but a small market ($200K/yr) keeps it on the watch list. **Market/yr** **$200K** **Growth (1y)** **+269.8%** **Products** **58** **Brands** **17** was 12 a year ago **Sellers** **113** **Price range** **$6.68–$69.20** **Returns** **3.5%** **Rating** **4.5★** **Worth a look** Scored 55/100 across market size, growth, competition, quality gap, and returns. Market sizeGrowthCompetitionQuality gapReturns Market size **10** ×0.30 Growth **83** ×0.30 Competition **77** ×0.20 Quality gap **39** ×0.10 Returns **72** ×0.10 ## **Demand** Weekly Amazon search volume, last 104 weeks — +269.8% year over year. 6K3KSpike '25Spike '26Jul '24Nov '24Mar '25Jul '25Nov '25Mar '26 ## **Seasonality** Monthly demand index across the year — 1.00 is average. JFMAMJJASOND Peak months: Mar · busiest ÷ quietest = 1.6× ## **Competition** - Fel-Pro47% - Dorman14% - ACDelco9% - National6% - A-Premium6% - GM GENUINE PARTS6% - Other (11 brands)12% Clicks spread well past the top 5 (36% combined) — an open shelf where new products get seen. 17 brands and 113 sellers compete here. **Brands** **17 **▲rising was 12 a year ago **Sellers** **113** **Top 5 brand share** **82%** #ProductBrandPriceRatingReviewsClick shareTrend 1 ![Dorman 635-518 Engine Rear Main Seal Cover Compatible with Select Models](https://m.media-amazon.com/images/I/31Mg5T9z6XL.jpg) [**Dorman 635-518 Engine Rear Main Seal Cover Compatible with Select Models**](https://www.amazon.com/dp/B009ZBSBMO) Dorman$49.634.6★1,16914%▼falling 2 ![FEL-PRO BS 40640 Engine Crankshaft Seal Kit for Chevrolet Silverado 1500](https://m.media-amazon.com/images/I/3195Eqfl2WL.jpg) [**FEL-PRO BS 40640 Engine Crankshaft Seal Kit for Chevrolet Silverado 1500**](https://www.amazon.com/dp/B000C2GA1Y) Fel-Pro$21.594.8★2,11210%▲rising 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**](https://www.amazon.com/dp/B082X9HMHG) A-Premium$36.374.1★3496%▼falling 4 ![FEL-PRO TCS 46117 Engine Crankshaft Seal Kit for Ford F-150](https://m.media-amazon.com/images/I/419pcB85n9L.jpg) [**FEL-PRO TCS 46117 Engine Crankshaft Seal Kit for Ford F-150**](https://www.amazon.com/dp/B002LWQ1MQ) Fel-Pro$8.374.7★4953%—flat 5 ![FEL-PRO TCS 46051 Engine Crankshaft Seal Kit for Honda CR-V](https://m.media-amazon.com/images/I/319EgBxuJCL.jpg) [**FEL-PRO TCS 46051 Engine Crankshaft Seal Kit for Honda CR-V**](https://www.amazon.com/dp/B000Q0R598) Fel-Pro$8.344.7★5353%—flat 6 ![FEL-PRO BS 40666 Rear Main Seal Set](https://m.media-amazon.com/images/I/41D30iIVx-L.jpg) [**FEL-PRO BS 40666 Rear Main Seal Set**](https://www.amazon.com/dp/B000CNKXYS) Fel-Pro$11.164.7★2593%▲rising 7 ![FEL-PRO BS 40644 Engine Crankshaft Seal Kit for Ford F-150](https://m.media-amazon.com/images/I/41u7DnxxMIL.jpg) [**FEL-PRO BS 40644 Engine Crankshaft Seal Kit for Ford F-150**](https://www.amazon.com/dp/B000C2E85Y) Fel-Pro$19.714.6★3813%—flat 8 ![FEL-PRO BS 40620 Engine Crankshaft Seal Kit for Ford F-150](https://m.media-amazon.com/images/I/31L55J-1PKL.jpg) [**FEL-PRO BS 40620 Engine Crankshaft Seal Kit for Ford F-150**](https://www.amazon.com/dp/B000C2G9T2) Fel-Pro$11.574.5★3753%—flat 9 ![ACDelco Gold 223830 (19340181) Crankshaft Front Oil Seal](https://m.media-amazon.com/images/I/31F5cbJelsL.jpg) [**ACDelco Gold 223830 (19340181) Crankshaft Front Oil Seal**](https://www.amazon.com/dp/B009IWX6I4) ACDelco$10.883.6★2413%—flat 10 ![FEL-PRO BS 40656 Engine Crankshaft Seal Kit for Chevrolet K1500](https://m.media-amazon.com/images/I/41CfHt0scaL.jpg) [**FEL-PRO BS 40656 Engine Crankshaft Seal Kit for Chevrolet K1500**](https://www.amazon.com/dp/B000C2CECS) Fel-Pro$21.544.8★5452%—flat 11 ![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](https://m.media-amazon.com/images/I/413Pzg157lL.jpg) [**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**](https://www.amazon.com/dp/B0CZLBB9GP) AUTOBABA$36.044.6★1232%—flat 12 ![FEL-PRO BS 40430 Engine Crankshaft Seal Kit for Honda Civic](https://m.media-amazon.com/images/I/31Ji6ij-+4L.jpg) [**FEL-PRO BS 40430 Engine Crankshaft Seal Kit for Honda Civic**](https://www.amazon.com/dp/B000C2G9XI) Fel-Pro$10.914.5★2852%—flat 13 ![GM Genuine Parts 89060436 Crankshaft Rear Main Seal](https://m.media-amazon.com/images/I/31ZemC3N5-L.jpg) [**GM Genuine Parts 89060436 Crankshaft Rear Main Seal**](https://www.amazon.com/dp/B07FZFVXL6) GM GENUINE PARTS$27.164.7★1832%—flat 14 ![FEL-PRO BS 40520 Engine Crankshaft Seal Kit for Chevrolet C1500](https://m.media-amazon.com/images/I/31fCQfMzKsL.jpg) [**FEL-PRO BS 40520 Engine Crankshaft Seal Kit for Chevrolet C1500**](https://www.amazon.com/dp/B000C2G9U6) Fel-Pro$13.934.8★1842%—flat 15 ![FEL-PRO BS 40684 Engine Crankshaft Seal Kit for Ram 1500](https://m.media-amazon.com/images/I/31TSqNTg7sL.jpg) [**FEL-PRO BS 40684 Engine Crankshaft Seal Kit for Ram 1500**](https://www.amazon.com/dp/B000Q0U75W) Fel-Pro$27.114.4★1652%—flat **~~Showing 15 of 58 — show all ~~** ## **Product shelf** All 58 tracked products in this niche. Top sellersNewestTrending [![Dorman 635-518 Engine Rear Main Seal Cover Compatible with Select Models](https://m.media-amazon.com/images/I/31Mg5T9z6XL.jpg)**Dorman 635-518 Engine Rear Main Seal Cover Compatible with Select Models** Dorman**$49.63**4.6★1,169 reviews](https://www.amazon.com/dp/B009ZBSBMO) [![FEL-PRO BS 40640 Engine Crankshaft Seal Kit for Chevrolet Silverado 1500](https://m.media-amazon.com/images/I/3195Eqfl2WL.jpg)**FEL-PRO BS 40640 Engine Crankshaft Seal Kit for Chevrolet Silverado 1500** Fel-Pro**$21.59**4.8★2,112 reviews](https://www.amazon.com/dp/B000C2GA1Y) [![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 reviews](https://www.amazon.com/dp/B082X9HMHG) [![FEL-PRO TCS 46117 Engine Crankshaft Seal Kit for Ford F-150](https://m.media-amazon.com/images/I/419pcB85n9L.jpg)**FEL-PRO TCS 46117 Engine Crankshaft Seal Kit for Ford F-150** Fel-Pro**$8.37**4.7★495 reviews](https://www.amazon.com/dp/B002LWQ1MQ) [![FEL-PRO TCS 46051 Engine Crankshaft Seal Kit for Honda CR-V](https://m.media-amazon.com/images/I/319EgBxuJCL.jpg)**FEL-PRO TCS 46051 Engine Crankshaft Seal Kit for Honda CR-V** Fel-Pro**$8.34**4.7★535 reviews](https://www.amazon.com/dp/B000Q0R598) [![FEL-PRO BS 40666 Rear Main Seal Set](https://m.media-amazon.com/images/I/41D30iIVx-L.jpg)**FEL-PRO BS 40666 Rear Main Seal Set** Fel-Pro**$11.16**4.7★259 reviews](https://www.amazon.com/dp/B000CNKXYS) [![FEL-PRO BS 40644 Engine Crankshaft Seal Kit for Ford F-150](https://m.media-amazon.com/images/I/41u7DnxxMIL.jpg)**FEL-PRO BS 40644 Engine Crankshaft Seal Kit for Ford F-150** Fel-Pro**$19.71**4.6★381 reviews](https://www.amazon.com/dp/B000C2E85Y) [![FEL-PRO BS 40620 Engine Crankshaft Seal Kit for Ford F-150](https://m.media-amazon.com/images/I/31L55J-1PKL.jpg)**FEL-PRO BS 40620 Engine Crankshaft Seal Kit for Ford F-150** Fel-Pro**$11.57**4.5★375 reviews](https://www.amazon.com/dp/B000C2G9T2) ## **Reviews** 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-Overall40% - Leak-Proof9% - Compatibility-Overall9% - Defective Material/Parts8% - Value For Money8% - Advertised Vs Actual Product7% - Product Condition3% - Quality-Overall3% - Maintenance And Repair2% - Assembly/Installation2%