Def

Just a tip to save money on DEF.
Go to a truck stop that has DEF at the fuel pump.
That nozzle will fit into the ADBLUE bottles - or- fill a jug and refill your ADBLUE bottle as needed.
MUCH cheaper that way. About $3.00 per gal.

Yup...I just fill it up straight from the pump...
I don't open it full blast to avoid the "water hammer" effect, but take 2-3 minutes on dribble to fill it up.
One warning...just a tiny bit of evaporation will cause lots of crystals to form....have seen it to the extent that most Trucking companies say to add Only full unopened bottles of DEF, to avoid issues (or from a pump).

it was 2.79/gal last time i filled a 2.5gallon jug. you also had to pay before you pump, you get some odd stares when only asking for 5 gallons of def.

Still at factory fill with phase 1 fix o the Passat, sitting just over 12K miles. I'm thinking the stage 2 tune may have reduced/eliminated the DEF consumption.

I think DEF is not expensive enough to worry about saving a few cents on it anyway. Besides, sooner or later the SCR system is going to have some wallet flushing event happen and you'll probably want to delete it anyway. It seems they cannot get these systems to work reliably and long term, and the parts prices are a bit nuts.

Some of the tunes allow the system to remain intact, it just either reduces its DEF use or renders it inoperative altogether. My friend's 1500 Ram has an SCR neutering tune. All the parts are still there, they are just along for the ride.