To add transmission fluid, follow these key steps:

1. Warm up the car by running the engine for about 15 minutes and park it on level ground with the engine running in “Park.”
2. Locate the transmission fluid dipstick (usually with a red or orange handle) and remove it.
3. Insert a clean funnel into the dipstick tube.
4. Slowly pour the correct type of transmission fluid (as per your vehicle’s owner manual) into the funnel in small amounts.
5. Check the fluid level frequently by wiping, reinserting, and pulling out the dipstick until the fluid reaches the “Full” or “Max” line.
6. Avoid overfilling to prevent transmission damage.
7. Once done, securely replace the dipstick or cap and turn off the engine.

Make sure to use the right type of transmission fluid, keep the engine idling during the process, and always work on level ground for an accurate reading. Using a transmission-specific funnel helps prevent spills. This method applies mainly to automatic transmissions and details may vary by vehicle make and model.