Took my truck to the dealer for oil leak and they replaced oil pan gasket. The oil leak is back and now I am going back to dealership. Any thoughts ...

Took my truck to the dealer for oil leak and they replaced oil pan gasket. The oil leak is back and now I am going back to dealership. Any thoughts on what it might be? Rear main seal? 20,000 miles on the truck.

My guess would be either the rear main seal or the ream main seal housing gasket.

hope this can help you. I found the following TSB. This might be the issue. 05-06-01-034J:Engine Oil Leak at Rear Cover Assembly Area
(Engine Block Porosity RTV Repair Procedure) - (Nov 12, 2009)

Models: 2004-2007 Buick Rainier
2008-2009 Buick LaCrosse Super, Allure Super (Canada Only)
2005-2010 Cadillac CTS-V
2007-2010 Cadillac Escalade, Escalade ESV, Escalade EXT
2003-2009 Chevrolet TrailBlazer
2003-2010 Chevrolet Corvette
2004-2006 Chevrolet SSR
2005-2010 Chevrolet Silverado, Silverado SS
2006-2007 Chevrolet Monte Carlo SS
2006-2009 Chevrolet TrailBlazer SS, Impala SS
2007-2010 Chevrolet Avalanche, Suburban, Tahoe
2009-2010 Chevrolet Colorado Pickup
2010 Chevrolet Camaro
2003-2009 GMC Envoy
2003-2010 GMC Sierra
2004-2005 GMC Envoy XUV
2007-2010 GMC Yukon XL, Yukon Denali, Yukon XL Denali
2009-2010 GMC Canyon
2004-2006 Pontiac GTO
2005-2008 Pontiac Grand Prix GXP
2008-2009 Pontiac G8 GT
2009 Pontiac G8 GXP
2005-2009 Saab 9-7X 5.3i
2008-2009 Saab 9-7X Aero
2003-2010 HUMMER H2
2006-2010 HUMMER H3
with 5.3L, 5.7L, 6.0L, 6.2L, 7.0L VORTEC™ GEN III or GEN IV V8 Engine (All Aluminum Block) (RPOs L33, LC9, LH6, LH8, LH9, LM4, LS4, LS1, LS6, L76, L77, LFA, LZ1, LS2, L92, L94, L99, L9H, LS3, LS9, LSA, LS7)

This bulletin is being revised to add RPOs and model years. Please discard Corporate Bulletin Number 05-06-01-034I (Section 06 -- Engine/Propulsion System).
Condition

Some customers may comment on an engine oil leak.

Cause
Upon initial diagnosis, it may be determined that the leak is coming from the rear cover gasket. This condition may be caused by engine block porosity on the sealing surface. This issue pertains to aluminum block applications only.

Correction
Follow the steps for Oil Leak Diagnosis in SI to determine the source of the leak. If the leak has been diagnosed as coming from the engine rear cover assembly, refer to Engine Rear Cover Replacement in SI and remove the engine rear cover assembly. Inspect the engine block and engine rear cover for porosity on the mating surfaces.
• If porosity is found on the engine rear cover (see illustration below), replace the engine rear cover assembly, GM P/N 12633579.
• If porosity is found on the engine block, use the following procedure to apply RTV to repair the engine block porosity.

The porosity issue is in the gasket sealing surface at the top of the cover, near the high pressure oil crossover port. Refer to the picture below. The oil leaks by the gasket and runs down the side of the cover, and may appear to be a leak at the t-joint area of the cover. The fix is to replace the cover with GM P/N 12633579. Also, if porosity is found anywhere on the sealing surface of the engine block, use the following procedure to apply RTV to repair the engine block porosity. Refer to the illustration below.

Important: Clean any residual oil from the block and cover before applying the sealant in the next step.

1. Wipe a small amount of RTV, P/N 12378521 (in Canada, use P/N 88901148), onto the surface using a plastic scraper to fill the porosity.
2. Remove any excess RTV material, especially from inside the high pressure oil passage. Refer to #1 in the above illustration.
3. The joint may be closed immediately after applying the RTV. Total joint time after the RTV has been applied must be under 20 minutes.

Important: Refer to Engine Rear Cover Replacement in SI and follow the tightening specifications and sequence.

4. Reinstall the engine rear cover using a new gasket and a new crankshaft rear main seal. Refer to Engine Rear Cover Replacement in SI.
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Has any body had that Tsb done with success and has there been any oil leaking sense?

wow that is very informative

I'm sure it is successful, otherwise GM would have come out with another fix.

Porosity simply put is a poor casting of the aluminum block and or cover assy. So the fix is a quick spackling of rtv silicone and send you on your way. Great.Real confidence inspiring.

RTV is good stuff. I think the holes they are addressing here are really small. I use RTV to seal the ends of old small block (Chevrolet) engine intake manifolds. They make a gasket for it, but they always leak. I know some manufacturers (Mazda) used only RTV for their oil pans (no gasket at all) and it worked better than the available service gasket would. I wouldnt lose any sleep over it if I had to use it for my truck, and I am really anal about making a proper repair.

I had the AFM deflector (in the oil pan-which the oil pan gasket WAS leaking and was one of the the reasons for taking the truck in) and new redesigned valve cover installed on my truck and it looks like that there is a gasket and some RTV used towards the back of the block to seal up the oil pan (where it was leaking in the first place). It looks like a good and proper repair. I'm content. The RTV used now in days is probably better than most gaskets out there if applied properly.

Well got my truck back from the dealer and they said it was residual oil from when they changed the oil pan gasket. Also noticed oil around rack & pinion. They put dye in both oil and power steering fluid and told me to come back in 500 miles.