FYI, we recently stopped at a MB dealer to pick up an adblue DEF bottle, and learned they are now selling it in 2.5 gallon jugs that don't have the neat "burp" fill design and at a price relatively competitive with Walmart. The parts guy said it might just have been a distributor difference, but in the Knoxville, TN dealership they hadn't seen the smaller adblue bottles in about 6 months.
Yes, the 2.5 gallon is overall cheaper (by far), which is a good thing.
Just wanted to alert folks - don't toss those old adblue bottles since you can easily refill them from the larger DEF jugs and they might not be available in the future. We like the no mess, no spill aspect of the adblue bottle.
Michelle