When I first bought my truck in Nov 04, I thought I was going crazy because I couldn't find the transmisson dipstick. After researching the manual and talking to the dealership, I discovered that it was a totally sealed transmission. How realiable is that? All other transmissions (with a dipstick) require changing the fluid at 30-40K intervals. Am I to believe that transmissions with a dipstick are more prone to getting dirt, grime, etc, inside therefore degrading the fluid and requiring a fluid change/flush? I just don't see the "big" difference between this particular transmission and any other transmission that requires fluid change at some point.