Park on a level surface and let the transmission cool
Gather the correct fluid, drain pan, funnel, rags, gloves, and filter gasket parts if needed
Check the transmission fluid level and condition
Inspect for leaks around the pan, seals, lines, and cooler
Drain the old transmission fluid
Remove the transmission pan
Clean the pan thoroughly
Clean the magnets in the pan
Replace the transmission filter
Replace the pan gasket
Reinstall the pan and tighten bolts evenly
Refill with the correct type and amount of transmission fluid
Start the engine and cycle through all gear positions
Recheck the fluid level and top off as needed
Inspect again for leaks
Clear any stored transmission codes if applicable
Test drive and recheck fluid level and shifting
Replace damaged hoses, seals, or worn parts if needed
Service the transmission cooler and lines if contamination is present
Use a professional flush only if recommended for your transmission type
Seek a mechanic if there is slipping, grinding, burning smell, or metal debris in the fluid