2018 Chevrolet Tahoe Transmission Fluid & Service

Quick answer

• Transmission Make/Model: GM 8L90 (RPO M5U)
• OEM Fluid Spec: DEXRON HP (GM Part Number 19417577 or equivalent)
• Drain & Fill Capacity: Approximately 6-7 quarts (verify with dipstick/level check procedure)
• Full Overhaul Capacity: Approximately 11.8 quarts (11.2 liters)
• Filter OEM Part Number: Verify with dealer or service manual (typically AC Delco 24278401 or equivalent)
• Recommended Service Interval: Normal duty: 97,500 miles or 7 years; Severe duty/towing: 45,000 miles or 3 years.

Fluid type explained

The 2018 Chevrolet Tahoe with the 5.3L V8 engine most commonly comes equipped with the General Motors 8L90 eight-speed automatic transmission (RPO M5U). This advanced transmission requires a very specific fluid to ensure optimal performance, longevity, and proper shifting characteristics. The correct fluid for the 8L90 is DEXRON HP. It is critical to use only DEXRON HP or an officially licensed equivalent that meets the GM DEXRON HP specification. Using any other type of automatic transmission fluid (ATF), such as conventional DEXRON VI, DEXRON III, or multi-vehicle ATFs, can lead to premature transmission wear, shuddering, shift quality issues, and potential transmission failure. Always verify the fluid specification with your owner's manual or a GM service manual.

Service procedure

Proper transmission fluid service for the 8L90 transmission is crucial. Unlike some older transmissions, simply draining the pan and refilling is generally not enough for a complete fluid exchange due to the complexities of the valve body, torque converter, and cooling lines. There are two primary service methods:

• Drain & Fill: This involves draining the fluid from the transmission pan and refilling with new fluid. This method replaces only a portion of the total fluid capacity (typically 50-60%). While better than nothing, it leaves a significant amount of old, contaminated fluid mixed with the new. A