Do You Leave the Car Running When Adding Transmission Fluid?

1. Consult Your Owner’s Manual

The manufacturer’s specifications always take precedence. Look for the “Transmission Fluid” section in your vehicle’s manual for exact procedures.

2. Determine Your Transmission Type

Automatic transmissions typically require the engine to be running when checking fluid level, but often off when adding fluid.
Manual transmissions usually require the engine to be off for both checking and adding fluid.

3. Prepare Your Vehicle

– Park on a level surface
– Engage the parking brake
– For automatic transmissions: Shift through all gears before returning to Park/Neutral
– Allow the engine to reach normal operating temperature when checking the fluid level

4. Engine Status for Fluid Addition

For most automatic transmissions:
– The engine should be running when checking the fluid level
– The engine should be off when adding fluid

For manual transmissions:
– The engine should always be off for both checking and adding fluid

5. Adding Fluid Properly

– Use a funnel to prevent spills
– Add small amounts at a time (typically 1/4 to 1/2 pint increments)
– Wait 1-2 minutes between additions for the fluid to settle
– Check the dipstick (if equipped) after each addition

6. Verifying Correct Fluid Level

– For automatic transmissions with the engine running: The fluid should be between the “Hot” marks on the dipstick
– For manual transmissions: The fluid should reach the fill hole opening when level
– Wipe the dipstick clean between checks for accurate readings