See if someone know what to do.
When I start the engine I hear a dazzling noise from the automatic transmission when shifter is in Neutral or Parking. It only happens when the motor is cold started. After a few minutes the noises disappers. And I can only start the engine (when cold) in N. As soon as it is warm there is no problem to start the engine in P.
I use a Dexron III oil from Quaker State for the transmission. The engine is a 318 from ´85. Transmmision unknown (904 or perhaps a 727). And no, it´s not a Challenger. It´s my Valiant