Here's a nice little FREE tip for you! I can't count the number of empty Blue DEF boxes I've seen next to gas station trash cans. Once people top off their trucks, they leave them next to the trash can to be thrown away by the gas station attendants. These things seem to be all over the place. I'm sure you've noticed them around as well and if you haven't, I am positive you'll pay attention to them now.
If you spot one of these discarded boxes at your local gas station, unscrew the collapsible spout and keep it! Once you get home, wash it out thoroughly with clean water to flush out all of the DEF fluid. Do not use soap to clean it, just use clean water.
This FREE collapsible spout will attach to many other wide mouth bottles such as coolant bottles and motor oil bottles. I know the oil filler neck on Vanagons extends out to help for filling, but sometimes I still end up making a mess trying to add oil to my engine through the license plate door. The same goes for the coolant tank. This spout will allow you to top off your fluids without spilling a drop.
Be sure to note that once you use the spout for one type of fluid (ie. coolant or motor oil), never use it for any other type of fluid. Just grab another spout once you find another empty Blue DEF box at the gas station.
Once you're done using the collapsible spout to top off your fluid, just collapse the spout back down and it will self-drain whatever is left in the nozzle back into the bottle. Unscrew the spout and store it in a Zip-Loc bag for safe and clean keeping.
These are much easier to store in your van than the traditional fluid funnels that can be purchased at the local auto parts store.