ORAEVY Rear Main Seal Gasket Set for GM LS Engines — BS40640 Fits 4.8L–6.2L, OEM Replacement

ORAEVY BS 40640 Rear main seal gasket set is a direct-fit replacement for GM LS-series Vortec engines designed to stop crankshaft oil leaks and restore a reliable seal on 4.8L–6.2L applications.

If your Chevy, GMC or related GM vehicle with an LS-series engine is leaking oil at the rear of the crankshaft, this gasket and seal kit gives you the parts needed to reseal the rear main area. The kit replaces OEM numbers 89060436 and 12639249 and fits a wide range of GM Vortec engines — from small-block 4.8L truck units up to 6.2L performance engines — covering many Chevrolet, GMC, Cadillac and Buick models across two decades.

Which vehicles and engines will this gasket set fit?

This kit is made for GM LS-family Vortec engines found in many trucks, SUVs and passenger cars built roughly from 1999–2020. It covers common displacement variants used by Chevrolet and GMC and is compatible with both truck and SUV applications.

• Fits 4.8L, 5.3L, 5.7L, 6.0L and 6.2L LS engines (LS1, LS2, LS3, LS6, LQ4, LQ9 equivalents).
• Compatible vehicles include Silverado, Sierra, Suburban, Tahoe, Yukon, Avalanche, Trailblazer, Envoy, Escalade, Camaro and many more.
• Replaces OEM part numbers 89060436 and 12639249 (BS 40640).

What comes in the package and what quality can I expect?

The ORAEVY set arrives with the rear main gasket and seal components plus simple installation aids. Parts are manufactured to meet or exceed typical equipment specifications and are engineered to resist oil, heat and crankcase pressure over time.

• Includes one full rear main gasket/seal set, a pair of installation gloves and a small cleaning brush.
• Materials designed to withstand high temperatures and exposure to engine oil.
• 12-month limited warranty and seller support for fitment or product concerns.

How should I prepare and install the rear main seal gasket set?

Installing a rear main seal typically requires removing the transmission or transaxle to access the crank flange. Proper cleaning and inspection of mating surfaces prevents repeat leaks; follow vehicle service manual torque specs for reassembly.

• Drain oil and remove transmission to access the rear main area safely.
• Use the included brush and a suitable solvent to clean the crank housing and flange surfaces thoroughly.
• Install seal and gasket squarely; torque bolts to manufacturer specs and replace any worn fasteners or bearings as needed.

Will this stop my oil leak permanently?

A correctly sized, well-installed seal and gasket can eliminate leaks caused by worn or damaged rear main seals. Long-term success depends on correct fitment, clean mating surfaces and addressing any related causes like crankshaft flange wear or excessive crankcase pressure.

• Replace the seal when mating surfaces are clean and damage-free for best results.
• Inspect crankshaft flange for grooves—machine or replace if required before seal installation.
• Repair or diagnose excessive crankcase pressure sources to avoid future failure.

Who is this for: The ORAEVY BS 40640 rear main seal gasket set is for DIY mechanics, professional technicians and fleet maintainers working on GM LS-series V8 and V6 Vortec engines who need a cost-effective, OE-interchange replacement. It’s ideal if you’re restoring a leak-prone engine, performing a transmission service that exposes the rear main, or preparing an engine for long-term reliability.