Bulletin No.:

Service Bulletin

Date:

18-NA-150
January, 2022

INFORMATION
Subject:
Brand:

Chevrolet

GMC

6.6L Duramax Possible Oil Leak Path Information
Model:

Model Year:
from

to

Silverado

2017

2018

Silverado 2500/3500

2019

2022

Silverado 4500HD,
5500HD, 6500HD

2019

2022

Sierra

2017

2018

Sierra 2500/3500

2019

2022

VIN:
from

to

Engine:

L5P, L5D

Involved Region or Country

North America, Middle East, Israel, South America and Thailand.

Additional Options (RPOs)

Equipped with 6.6L Diesel Engine (RPO L5P or L5D)

This document is to help identify where to look for an oil
leak on the 6.6 Duramax engine.
Note: Please keep in mind that a leak on the top of the
engine will trail down the back side of the engine and
appear as a rear cover leak.

Copyright 2022 General Motors LLC. All Rights Reserved.

Transmission:

Please use the illustrations below as a guide of where
to look for a potential oil leak. These Illustrations are of
a L5P engine; the L5D would be similar.

Page 2

January, 2022

Bulletin No.: 18-NA-150

Possible Oil Leak Paths

5053868

Legend
(1)
(2)
(3)
(4)
(5)
(6)
(7)

GASKET, VLV RKR ARM CVR (Rocker
Cover Gasket)
GASKET, CYL HD (Head Gasket)
SENSOR, ENG OIL PRESS (Oil
Pressure Sensor)
PLUG, ENG BLK OIL GAL (Plugs in
Block Qty 4)
SEAL, OIL LVL IND TUBE (O-Ring on
Oil Indicator Tube)
SEAL, ENG OIL LVL IND SW (Oil Level
Sensor)
SEAL, OIL PAN DRN PLUG (Oil
Drain Plug)

5053869

Plugs and Gaskets in Oil Cooler and Filter

Bulletin No.: 18-NA-150

January, 2022

5053871

Ghost view of the Oil Cooler Cover to reveal 2 O-rings
(SEAL, ENG OIL CLR).

5053872

Legend
(1)
(2)

GASKET, TURBO OIL FEED PIPE
(Turbo Oil Feed Pipe into Block, Turbo
Pipe removed for picture only)
PLUG, ENG BLK OIL GAL (Section cut
through Flywheel housing to show 2
plugs on the back of the engine block )

Page 3

5053874

Legend
(1)

GASKET, TURBO OIL RTN PIPE (Turbo
Oil Drain Pipe Gaskets (Quantity 3))

Page 4

January, 2022

Bulletin No.: 18-NA-150

5053875

Legend
(1)
(2)

(3)
SEAL, OIL FIL CAP (Oil Separator
Gaskets)
GASKET, TURBO OIL FEED PIPE
(Turbocharger Oil Gasket (2) )

PLUG, CYL HD OIL GAL (Upper Oil
Pan Plug)

5053879

5053878

Legend
(1)
(2)

PLUG, ENG BLK OIL GAL (Oil
Gallery Plug)
RTV (Oil Pan Seals)

Legend
(1)
(2)

RTV (Front Cover Seal)
SEAL, CR/SHF FRT OIL (Front
Bearing Seal)

Bulletin No.: 18-NA-150

January, 2022

Page 5

5053880

Note: (Flywheel Housing has been removed for clarity
of picture)
Legend
(1)
(2)

RTV (Flywheel Housing Seal)
SEAL, CR/SHF RR OIL (Rear
Bearing Seal)

Version

5

Modified

Released May 04, 2018
Revised July 25, 2018 - Added the 2019 Model Year.
Revised June 24, 2019 - Added 2500/3500 to Models and 2020 to Model Year section.
Revised October 19, 2020 - Added 2021 Model Years to 2500/3500 models and added
2019–2021 Silverado 4500, 5500 and 6500 HD Models and added RPO L5D.
Revised January 07, 2022 - Added 2022 to Model Year.

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.

WE SUPPORT VOLUNTARY
TECHNICIAN
CERTIFICATION