[MJN]

what Delco filter have you been running? What are your change intervals and what oil are you running? I've run PF61's on my 6.0L's in the past with no issues and currently I use AMSOIL Ea15k50 filters. I also use AMSOIL 5w30XL oil, change at 10,000 miles and have oil analysis done on each oil change.

Typically when you begin losing oil pressure the filter has plugged up and is restricting flow. This issue has shown up on 5.3L's with AFM and GM released a service bulletin about it and to begin using AC Delco UPF48R filters. The 6.0L doesn't have AFM so that is not an issue on that engine- unless you're running beyond recommended intervals, using low quality oil or have other issues. Currently AMSOIL recommends using WIX 57060 or Donaldson P550794 on 5.3L's.

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2012 GMC Truck Sierra - 4WD | Cheyenne, Sierra, Silverado VIN C/K Service Manual | Document ID: 4211936
#PIP5276D: SES Lamp P0521 Setting After An Oil Change And Or Low Oil Pressure Indicated On The Instrument Panel - (Jun 8, 2015)
Subject: SES Lamp P0521 Setting After An Oil Change And Or Low Oil Pressure Indicated On The Instrument Panel

Models: 2007-2013 Cadillac CTS-V, Escalade
2007-2013 Chevrolet A****, Camaro SS, Colorado, Corvette, Express, Silverado, S****, T***
2007-2013 GMC Canyon, Sierra, Savana, Y***
with a V8 Engine (RPOs L20, L77, L94, L96, L99, L9H, LC8, LC9, LH9, LMF, LMG, LY6, LZ1)
The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI.

Condition/Concern
A concern of a P0521 Setting After an oil change and or low oil pressure indicated on the instrument panel.

Recommendation/Instructions
If you are working on a Gen4 V8 that is setting a DTC P0521 and or low oil pressure indicated on the instrument panel in cold or hot weather and the engine is currently equipped with a PF48E oil filter, replace with a UPF48R oil filter if one is available.

Note: Only use the UPF48R oil filter if theGen4 V8 is setting a DTC P0521.

Warranty Information
For vehicles repaired under warranty use:

Labor Operation
Description
Labor Time
4065530
Oil Filter Replacement
Use Published Labor Operation Time
Please follow this diagnostic or repair process thoroughly and complete each step. If the condition exhibited is resolved without completing every step, the remaining steps do not need to be performed.

GM bulletins are intended for use by professional technicians, NOT a "do-it-yourselfer". They are written to inform these technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions, and know-how to do a job properly and safely. If a condition is described, DO NOT assume that the bulletin applies to your vehicle, or that your vehicle will have that condition. See your GM dealer for information on whether your vehicle may benefit from the information.