03 suburban, 157k miles. New Napa trans filter. Pulled A/T return line, hose to bucket, and flushed 4.5 gallons. Took that much before it came out bright red. Started with 3 gallons of Maxlife, but local stores were out, so I finished with 1.5 gallons of Valvoline DeXIII.
Next year, I'll do it again with full Maxlife or DexVI.