Well i used my 4l60e to test some theorys,about syn trans fluid.at 500 miles i flushed out reguler dex merc with mobil 1 syn trans fluid.I got a nelson tune with 100%tq mgt removed and installed, all my mods at once.Okay now i take this thing to 6100rpm in first and 2nd gear at least 2or 3 times a day.Also have used allens nice shift into od at 56oo rpms at WOTat least 4 times.Tow a 20ft lund boat.And show it no mercy.Launch in 4hi etc run in autotrac in the rain at 90mph plus. So today i drop pan at 23405 miles, and was amazed,there is very little metal on magnet Im sure someday it will go but who cares for the amount of abuse i show it.And it helps my brother is service mgr at chev.Thinking of 75 dry shot next