2018 Chevrolet Silverado 1500 Transmission Fluid & Service Spec

Quick Answer

• Transmission Make/Model: GM 8L90 (RPO M5U)
• OEM Fluid Spec: Dexron ULV Automatic Transmission Fluid
• Drain & Fill Capacity: Approximately 6.0-7.0 quarts (varies slightly by pan design and how much drains)
• Full Overhaul Capacity: Approximately 12.0 quarts
• Filter OEM Part Number: Verify with dealer or service manual – often internal to the transmission and not a routinely serviceable item for a simple drain and fill.
• Recommended Service Interval: 97,500 miles (normal duty) or 45,000 miles (severe duty/towing)

Fluid Type Explained: Dexron ULV

The 2018 Chevrolet Silverado 1500, when equipped with the 8L90 8-speed automatic transmission, utilizes a very specific automatic transmission fluid: Dexron ULV (Ultra Low Viscosity). It is absolutely crucial to use only Dexron ULV in this transmission. This fluid is specially formulated for modern, highly efficient transmissions with tight internal clearances and intricate hydraulic control systems.

Using any other type of fluid – even older Dexron VI or other multi-vehicle compatible fluids – can lead to immediate and severe transmission damage. Dexron ULV has a significantly lower viscosity than previous generations of ATF, which contributes to improved fuel economy and faster shift response. This low viscosity also helps to reduce drag and heat generated within the transmission.

Always ensure any fluid you purchase explicitly states "Dexron ULV" and meets the General Motors specification for your 2018 Silverado 1500 8-speed transmission. When in doubt, consult your owner's manual or a certified Chevrolet dealership for the correct fluid.

Service Procedure: Drain & Fill vs. Full Exchange

Servicing your 2018 Silverado 1500's 8L90 transmission can typically be done via a drain and fill method, or a more comprehensive flush/fluid exchange.

Drain & Fill

A drain and fill involves removing the pan, allowing the fluid to drain out, replacing the filter (if accessible and recommended for your service interval), and refilling with new fluid. For the 8L90, the fluid capacity for a drain and fill is typically around 6.0-7.0 quarts. This method replaces only a portion of the total transmission fluid, as a significant amount remains in the torque converter, valve body, and cooler lines. While less thorough, it is a viable option for routine maintenance if performed at the recommended intervals.

Note on Filter: For many modern transmissions like the 8L90, the internal filter is not designed for routine replacement during every fluid change. It's often a lifetime filter designed to last as long as the transmission itself, or it requires significant disassembly to access. Always verify the recommended filter service interval and procedure with your owner's manual or a Chevrolet service technical bulletin. If replacement is recommended, ensure you use the correct OEM part or an approved aftermarket equivalent.

Full Fluid Exchange (Flush)

A full fluid exchange, often referred to as a "flush," involves using specialized equipment to evacuate nearly all of the old fluid from the transmission and replace it with new fluid. This typically results in replacing the entire 12.0-quart capacity of the transmission.

While a full exchange is more thorough, it's important that it