it's a sealed fill tube.. apparently they (the transmissions) are very sensitive to moisture. To refill it after servicing you have to break the filler tube seal - use the special dipstick tool to measure the fluid at specific temperatures and then reseal the filler tube when done.. no permanent dipstick. The guy at the shop where I go also said the seals for the electronics going into the transmission are prone to failure.. and a royal PITA to change out