Bulletin No.: 25-NA-052

Service Bulletin

Date: March, 2025

INFORMATION
Subject:
Brand:

Buick
Cadillac
Chevrolet
GMC

Information on Flushing Oil Contamination from Cooling System
Model:

GM
Passenger
Cars and
Light/Medium
Duty Trucks

Model Year:

Build Date:

from

to

from

to

2000

2025

—

—

Engine:

Transmission
:

—

—

Involved Region or Country

North America, Argentina, Brazil, Bolivia, Chile, Colombia, Ecuador, Paraguay, Peru,
Uruguay, Venezuela, Europe, Kazakhstan, Uzbekistan, Russia, Middle East, Iraq, Israel,
Palestine, Japan, South Korea, China, Taiwan, Thailand, Singapore, Philippines,
Australia/New Zealand, Egypt, Other Africa

Cause

If you found oil in the coolant and the engine is otherwise healthy, this may be caused by
a leaking engine oil cooler.
Note: Over the counter detergents and chemicals not made for flushing an engine cooling system should not be used as they have not been validated against attacking the
seals, aluminum, or steel head gaskets in the engine.
If you find that the engine coolant is contaminated with oil, replace the engine oil cooler,
and perform the following procedure to clean the cooling system:
Note: Since the amount of flushing or time spent flushing is proportional to the amount of
oil in the coolant, there will not be a labor time assigned to this procedure.
• Use clock time.
• Initial Flush; to remove most of the oil from the system. This is the first and most important step.
• It is best to use hot water to flush the cooling system.

Information

− Only use hot water. The purpose of this step is to get as much of the oil out of the
system as possible. Flushing from multiple locations and in multiple directions is
key here. Keep flushing until most all the oil has been removed.
• Replace oil contaminated parts. At this point, there should be little to no oil in the system.
⇒ Replace all rubber parts that have come in contact with the oil.
⇒ Replace the thermostat and gasket.
• Do not replace the coolant bottle in this step.
⇒

Flush the system again, this time with a chemical flushing agent. The Prestone with
Oil and Fuel Remover is recommended. Follow the directions on the label.
• Once finished and before filling the vehicle with coolant, change the coolant bottle and
cap.

Important: Service agents must comply with all International, Federal, State, Provincial, and/or Local laws
applicable to the activities it performs under this bulletin, including but not limited to handling, deploying,
preparing, classifying, packaging, marking, labeling, and shipping dangerous goods. In the event of a
conflict between the procedures set forth in this bulletin and the laws that apply to your dealership, you
must follow those applicable laws.

Service Procedure
Refer to Flushing in SI.

Copyright 2025 General Motors. All Rights Reserved.

Page 2

March, 2025

Bulletin No.: 25-NA-052

Parts Information
For USA, use:

6856055

For Canada, use:

6873700

Note: Follow the procedure in SI for additional parts that may be required for the repair.

Bulletin No.: 25-NA-052
Causal
Part

N/A

Description
Prestone MAX
Total Cooling
System Cleaner
(USA)
Prestone
COMMAND
Cooling System
Cleaner (Canada)

March, 2025
Part
Number

Qty

N/A

As Required

Page 3

Warranty Information
For vehicles repaired under the Powertrain coverage, use the following labor operation. Reference the Applicable
Warranties section of Investigate Vehicle History (IVH) for coverage information.
Labor
Operation
4089458*

Description

Labor Time

Coolant Flush to Remove
Oil from Cooling System

ST

*This is a unique Labor Operation for bulletin use only.
Version

2

Modified

Released March 04, 2025
Revised March 25, 2025 – Updated graphic for U.S. product and added Command
Cooling System Cleaner for Canada under Parts Information.

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.

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