I decided to change the filter and oil in the drive units on my z-force 54 cub cadet. I was able to drain oil and change filters with no problem, however, when I tried to refill the drivbe units (pumps) with oil through the expansion tank as recommended, the oil wouldn't go down. Acts like a air lock. I found the hoses from the tank to the pumps where routed such that it looks like a trap found in bathroom sinks. I cut cable ties to get hoses flattened somewhat and some of the oil flowed down okay. Called the dealer and he said to run the engine so the pumps will suck the oil down. Is this a good idea?