Changed fluid in 2003 Dodge Neon. Stick showing proper level at cold, nothing showing on stick when engine is hot. Notice some slippage when driving. Added about 10 pints. Where is the fluid? No leaks.

 

Quite possible you still need more fluid. Don't know how low it was before you added the 10 pints, but you are supposed to check the fluid after it has warmed up - it even says so on the dipstick.

Even if you get the fluid level up to proper level after it is warmed up, if it was so low before it was refilled that it damaged the tranny valve body, then you may still have slippage even when the fluid level is at the proper level.

Let's hope not. Good luck.