Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
Information On Ethylene Glycol In Transmission Fluid (08-07-30-035I)
Reference number: 08-07-30-035I
Supersedes refnos: 08-07-30-035, 08-07-30-035A, 08-07-30-035B, 08-07-30-035C, 08-07-30-035D, 08-07-30-035E, 08-07-30-035F, 08-07-30-035G, 08-07-30-035H
INFORMATION ON ETHYLENE GLYCOL IN TRANSMISSION FLUID
TECHNICAL SERVICE BULLETIN
| Affected Model(s): | 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) |
| Supercedes: | This bulletin has been revised to update applicable information throughout the bulletin. Please discard Corporate Bulletin Number 08-07-30-035H. |
SERVICE INFORMATION
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.
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. 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 ethylene glycol 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.
If ethylene glycol in the ATF from a leaking 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 transmission oil cooler replacement. This can help to prevent customer comebacks if the transmission oil cooler is leaking and reduce repair expenses by avoiding transmission oil cooler 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.
If ethylene glycol is found in the transmission, the following components MUST be replaced.
- Replace all the rubber-type seals.
- Replace all the composition-faced clutch plates and/or bands.
- Replace all the nylon parts.
- Replace the torque converter.
- Thoroughly clean and rebuild the transmission, using new gaskets and oil filter.
NO RELATED
Use the Manual With the Right Hardware
Pair factory procedures with proven DIY tools so the instructions are easier to execute.
Affiliate disclosure: We may earn a commission at no extra cost to you.
When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.