The past few days I have been noticing a slight grinding in my tranny. It doesn't seem like grinding in the traditional way, but more like it puts a small vibration through the rest of the car. It is like a really "fine" grind, if that makes any sense. I have the standard AOD with floor shift. Would it just be best to take it and get the fluid flushed? And if I do, should I get Mercon IV put in or do these trannys not work with IV?