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.

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.

Review moat

Great227.43

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

Great36%

top-5 click share — an open shelf

Conversion

Good4.0%

search→purchase rate — share of searches ending in a sale

Returns

Okay3.5%

return rate — above 5% kills the launch gate

Quality gap

Okay4.5★

avg incumbent rating — lower means beatable quality

Market size

Okay$200K

$200K/yr · 258K searches

Brand share

Okay82%

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

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.

Peak months: Mar · busiest ÷ quietest = 1.6×

Open Trend

Top rear main seal search terms

rear main seal135K/yr -14.3%2.3% conv.
crankshaft seal49K/yr -16.9%1.8% conv.
front crankshaft seal19K/yr -20.7%1.5% conv.
front main seal16K/yr -14.6%2.0% conv.
rear main seal kit19K/yr -21.6%2.3% conv.
crank seal10K/yr -8.7%2.4% conv.
crank shaft seal5K/yr +9.1%1.3% conv.
rear crankshaft seal5K/yr -27.0%1.3% conv.

All 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.

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

Dorman 635-518 Engine Rear Main Seal Cover Compatible with Select Models

Dorman$49.634.6★1,169 rev

FEL-PRO BS 40640 Engine Crankshaft Seal Kit for Chevrolet Silverado 1500

Fel-Pro$21.594.8★2,112 rev

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$36.374.1★349 rev

FEL-PRO TCS 46117 Engine Crankshaft Seal Kit for Ford F-150

Fel-Pro$8.374.7★495 rev

FEL-PRO TCS 46051 Engine Crankshaft Seal Kit for Honda CR-V

Fel-Pro$8.344.7★535 rev

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$36.04123 rev

2y ago

National 711024 Engine Crankshaft Seal

National$11.3451 rev

2y ago

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$36.3992 rev

3y ago

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$36.37349 rev

6y ago

GM Genuine Parts 89060436 Crankshaft Rear Main Seal

GM GENUINE PARTS$27.16183 rev

7y ago

What buyers say about rear main seal

What buyers praise and complain about, mined from review topics.

What buyers love

Size-Overall36%

“Fit perfect”

Quality-Overall22%

“Excellent product”

Leak-Proof16%

“Not leaking”

Advertised Vs Actual Product10%

“Works as it should”

Value For Money4%

“Good purchase for the price”

Assembly/Installation4%

“Easy install”

Efficiency4%

“Works great”

Safety Standards1%

“Seals the rear main as it should”

Amplification0%

“Best 4.0 RMS out there”

Ease Of Use0%

“Easier to guide and push in”

What buyers complain about

Leak-Proof38%

“Leaking”

Compatibility-Overall24%

“Doesn't work for d16y7 or d16y8”

Size-Overall11%

“ID is slightly smaller”

Quality-Overall7%

“Junk”

Durability6%

“Lasted 6 months and blew out”

Defective Material/Parts5%

“Received unusable part”

Thickness2%

“This is actually thicker than the factory cover”

Maintenance And Repair1%

“I replaced it before setting the engine in the new frame to save myself the headache of having to replace it later”

Lubrication1%

“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%

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.