The transmission does not engage (sometimes for several minutes) when putting it in drive or reverse. It seems to have more trouble engaging at normal operating temperature than when its cold. When the transmision whines (when it is engaged) then it will shift. Without the whining noise it will not shift. As the car warms up to normal operating temperature the whining noise begins to go away. What is causing this? What can I do to correct this? PLEASE HELP. Thank you