To change the transmission fluid in a Dodge Neon, drain the transmission pan, detach and clean the pan, remove the gasket, remove the O-ring sealer, replace the filter, and install a new gasket. Attach and tighten the transmission pan, and use a long-neck funnel to add fresh transmission fluid.

Gather a transmission filter service kit and fresh fluid. Place a large bucket under the transmission pan. If the transmission pan has a drain plug, remove it, and allow the fluid to drain into the bucket.

Remove the bolts from the pan on all sides but one. Break the seal on the pan by tapping it lightly with a mallet. Tilt the pan so it pivots on the side where the bolts are still attached, and allow the fluid to drain into the bucket. Remove the remaining bolts to detach the pan from the vehicle. Wipe the inside of the pan to clean it, and use a flat-head screwdriver to remove the gasket from the edges.

Unbolt, detach the clips or pull off the O-ring sealer of the filter to remove it, and discard the filter. Install the new filter, and install the new gasket. Attach the pan, and tighten it by the torque spec given in the manual or to just snug.

Add fresh transmission fluid through the dipstick slot and into the reservoir using a long-neck funnel. Turn on the engine, and allow it to idle for one minute. Step on the brake pedal, and move the gear stick to each selection until you reach Park. Allow the engine to run until the temperature reaches its normal position, and check the fluid level.