Originally Posted by Quasimodem
I have used a small funnel, but it takes a long time and I had to first move the fluid to a smaller container because the big one is too heavy to pour with one hand. Then the small funnel fills up and you have to wait for it to drain -- tedious.
As previously mentioned, there is a smaller container which is designed to screw onto the inlet in place of the cap. I havent ever had one of these, but I have read that others have adapted these to be able to refill them (apparently they are designed to be one-shot things), so if you buy one once, you can use it and refill it and use it again. Also, maybe you could cut the bottom off and use it as a funnel but you would probably need to attach it to a stand like I did in the above photo with the transmission oil funnel.
Was just at the dealer for service and they locally came up with a better fill adapter as the one supplied by BMW took 2 people. I was thinking about doing this already. Using one of the 1/2 gallon screw on bottles, (for the sedan) cut a slot open on the side of the bottle (2"x3") towards the bottom (when standing up) that would be facing up when screwed into the fill port. Then hold the fill valve open in the bottle by pushing in and putting on a hose clamp to keep it from moving and closing the valve. Just screw on the bottle onto the fill port, then slowly pour the DEF into the open slot. Do not fill the bottle completely as all the weight is being supported by the port. Also do not go too fast when the DEF tank is near full as once full and you want to remove the bottle, if any DEF is still in the bottle it will pour out when you unscrew it. Wash the bottle with water when done or any remaining DEF will crystalize.