It can happen. The Navara auto has a transmission cooler INSIDE the radiator. Damage that area - for example, land your front end on a rock - and you can cause the transmission cooler to puncture causing the contamination.
We've towed 1.8T for a fair few km and haven't had a problem. Our new 2.5T van will present a little more challenge but since we've decided to simply take our time and since we let the car slow on steep inclines until we're in first gear (this allows the engine to only be lightly loaded) we don't anticipate any problems.
Still considering the racing radiator and separate tranny cooler though. Nothing like making sure the thing can't self-harm. You'd do it for a friend, why not your own car???
