Bulletin No.: 08-07-30-035H

Service Bulletin

Date: May, 2024

INFORMATION
Subject:

Information on Water or Ethylene Glycol in Transmission Fluid

Models:

2025 and Prior GM Passenger Cars and Trucks (including Chevrolet
Medium Duty LCF Equipped with Gas Engine and 6L90 Transmission)
Equipped with Automatic Transmission
EXCLUDES Chevrolet Medium Duty LCF with Diesel Engine and Aisin
Transmission and Silverado MD with Allison Transmission (Must go to
Allison distributor)

This bulletin has been revised to add the 2025 Model Year, Important statement at
beginning of bulletin, and remove the address and list website for obtaining test kits.
Please discard Corporate Bulletin Number 08-07-30-035G.
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.
Water or ethylene glycol in automatic transmission fluid
(ATF) is harmful to internal transmission components
and will have a negative effect on reliability and
durability of these parts. Water or ethylene glycol in
ATF will also change the friction of the clutches,
frequently resulting in shudder during engagement or
gear changes, especially during torque converter clutch
engagement.
Indications of water in the ATF may include:
• ATF blowing out of the transmission vent tube.
• ATF may appear cloudy or, in cases of extreme
contamination, have the appearance of a strawberry milkshake.
• Visible water in the oil pan.
• A milky white substance inside the pan area.
• Spacer plate gaskets that appear to be glued to
the valve body face or case.
• Spacer plate gaskets that appear to be swollen or
wrinkled in areas where they are not compressed.
• Rust on internal transmission iron/steel components.

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If water in the ATF has been found and the source of
the water entry has not been identified, or if a leaking
in-radiator transmission oil cooler is suspected (with no
evidence of cross-contamination in the coolant
recovery reservoir), a simple and quick test kit is
available that detects the presence of ethylene glycol in
ATF. The “Gly-Tek” test kit, available from the Nelco
Company, should be obtained and the ATF tested to
make an accurate decision on the need for radiator
replacement. This can help to prevent customer
comebacks if the in-radiator transmission oil cooler is
leaking and reduce repair expenses by avoiding
radiator replacement if the cooler is not leaking. These
test kits can be obtained from: http://www.gly-tek.com
Test kits can be ordered through the website listed
above. Orders are shipped standard delivery time but
can be shipped on a next day delivery basis for an
extra charge. One test kit will complete 10 individual
fluid sample tests. For vehicles repaired under
warranty, the cost of the complete test kit plus shipping
charges should be divided by 10 and submitted on the
warranty claim under Net/Miscellaneous.
The transmission should be repaired or replaced based
on the normal cost comparison procedure.
Important: If water or coolant is found in the transmission, the following components MUST be replaced.
• Replace all of the rubber-type seals.
• Replace all of the composition-faced clutch plates
and/or bands.
• Replace all of the nylon parts.
• Replace the torque converter.

Page 2

May, 2024

Bulletin No.: 08-07-30-035H

• Thoroughly clean and rebuild the transmission,
using new gaskets and oil filter.
Important: The following steps must be completed
when repairing or replacing.
• Flush and flow check the transmission oil cooler
using J-45096.
• Thoroughly inspect the engine cooling system and
hoses and clean/repair, as necessary.

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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