Transmission Fluid Change

This procedure involves draining and replacing the automatic transmission fluid and filter on a 2014-2018 Chevrolet Silverado 1500 with the 8-speed automatic transmission (8L90).

Warnings

Tools required

Parts

• Transmission filter kit (includes filter and o-ring) × 1 — AC Delco 24278880 or equivalent
• Transmission pan gasket × 1 — AC Delco 24275865 or equivalent

Fluids

• ACDelco Dexron VI ATF — 5 qt

Preparation

1. Park vehicle on level surface and apply parking brake
2. Allow transmission to cool if vehicle was recently driven (minimum 30 minutes)
3. Raise vehicle and support securely on jack stands at frame contact points
4. Verify you have the correct Dexron VI fluid (do not use Dexron III or other substitutes)
5. Locate transmission pan at rear of transmission, behind the crossmember

Procedure

1. 1

   Position drain pan
   Position a large drain pan (minimum 12 quart capacity) beneath the transmission pan. The pan is located at the rear of the transmission, behind the rear crossmember. Fluid will drain from the rear edge first when the pan is loosened.
2. 2

   Loosen transmission pan bolts
   Using a 10mm socket, loosen all transmission pan bolts approximately 3-4 turns. There are approximately 17 bolts around the perimeter. Do not fully remove any bolts yet. Start at the front corners and work toward the rear to allow the pan to tilt and drain from the rear edge first.
   ⚠Fluid will begin dripping as bolts are loosened. Keep hands and face clear of the drain area.
3. 3

   Drain transmission fluid
   Once fluid begins dripping steadily from the rear of the pan, carefully remove the rear bolts first, allowing the pan to tilt downward at the rear. Support the pan with one hand as you remove the remaining bolts to prevent it from falling. Lower the pan carefully and allow all fluid to drain completely. This will take several minutes.
4. 4

   Remove and clean pan
   Once fully drained, remove the transmission pan completely. Empty any remaining fluid from the pan into the drain pan. Inspect the pan bottom for metal shavings or debris (small amounts are normal). Clean the pan thoroughly with solvent and allow to dry. Remove the old gasket material from both the pan and transmission housing using a scraper, being careful not to gouge the sealing surfaces.
5. 5

   Remove old transmission filter
   Locate the transmission filter inside the transmission housing. It is held by two bolts and an o-ring seal. Remove the two filter mounting bolts and pull the filter straight down to remove. Inspect the o-ring seal location on the transmission housing and clean any debris from the sealing surface.
   Torque spec

   Sensor Bolts14 Nm (10 lb-ft)
6. 6

   Install new transmission filter
   Lubricate the new o-ring (included with filter kit) with a small amount of clean Dexron VI fluid. Install the new o-ring onto the filter inlet tube. Insert the new filter straight up into the transmission housing, ensuring the o-ring seats properly. Install the two filter mounting bolts and torque to specification using a criss-cross pattern.
   Torque spec

   Sensor Bolts14 Nm (10 lb-ft)
7. 7

   Install new pan gasket and pan
   Install the new gasket onto the transmission pan (some gaskets are adhesive-backed, others require positioning). Position the clean transmission pan up to the transmission housing, ensuring the gasket remains properly aligned. Start all pan bolts by hand, threading them in 2-3 turns to hold the pan in place.
8. 8

   Torque transmission pan bolts
   Using a torque wrench, tighten the transmission pan bolts in a criss-cross pattern starting from the center and working outward. Torque all bolts to 12 Nm (9 lb-ft) in multiple passes. First pass at 50%, second pass at 100%. This ensures even gasket compression and prevents leaks.
   Torque spec

   Pan Bolts20 Nm (15 lb-ft)
9. 9

   Refill transmission fluid
   Lower the vehicle to the ground. Locate the transmission dipstick tube on the passenger side of the transmission near the firewall. Remove the dipstick and insert a funnel. Add 5 quarts of Dexron VI ATF slowly. This replaces the fluid that was drained from the pan and filter.
10. 10

    Check fluid level and cycle transmission
    Start the engine and allow it to idle in Park. With your foot on the brake, shift through all gear positions (P-R-N-D and back to P), pausing 2-3 seconds in each gear. This circulates the new fluid through the transmission. Return to Park and let the engine idle for 2-3 minutes.
11. 11

    Verify fluid level and check for leaks
    With the engine running and transmission in Park, check the fluid level on the dipstick. The level should be in the HOT range after the transmission reaches operating temperature (usually after 5-10 minutes of idling or a short test drive). Add fluid if needed in small increments. Raise vehicle and inspect the transmission pan for leaks around the gasket. Retorque pan bolts if seepage is observed.

Reassembly

1. Ensure all transmission pan bolts are torqued to specification in a criss-cross pattern
2. Double-check fluid level with engine at operating temperature
3. Dispose of used transmission fluid at an approved recycling facility

Verification

• No fluid leaks visible around transmission pan after test drive
• Transmission fluid level is within HOT range on dipstick with engine running at operating temperature
• Transmission shifts smoothly through all gears without slipping or harsh engagement
• Fluid on dipstick appears clean and red (new Dexron VI is bright red)

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