I've noticed a grinding noise that occurs only after driving on the freeway for long trips (~100 miles). I notice it when I pull off the freeway and I'm accelerating normally. It doesn't seem to do it when it's cold. I just changed trans/rear diff fluid to Subaru Extra-S. It did this before the fluid change too. I changed fluid hoping to cure the problem. But no change. Im at about 34,5xx miles. TIA.