G'day to you, RobRover88! I do USAF fighter aircraft OT&E (operational test and evaluation) at Nellis AFB, Nevada, and one of our F-15E Strike Eagle pilots is an RAAF pilot on an exchange assignment (I also have a close Aussie friend who lives in ACT).
"Ad-Blu" is also the more common term here for DEF. I was just using the official nomenclature that appears on Ad-Blu containers. The D5's 18 liter Ad-Blue tank is good for about 4000 miles and it starts warning you at about 1000 miles remaining. Since the routine service interval for the Td6 is 16,000 miles (which amazes me--I change the oil in my garage half-way through that interval) I end up having to add Ad-Blu at least three times. I keep a good supply on hand and carry a 10 liter container on long trips.
D5s are not common here, either, which doesn't bother me since I've always preferred to own niche vehicles. The 2020 D5 bested the 2020 Jeep Grand Cherokee in a comparo article in the August 2020 issue of Motor Trend Magazine, which I just received in the post last week.