The chug cap was apparently designed only for carrying upright, and the numerous reviews must have only tested it that way. Because if you drive anywhere and lay it down, you need to tighten the cap quite a bit to not leak. On the second use, I couldn't unscrew the narrow-spout base... Even channel locks couldn't provide enough grip and leverage to bust it loose, and my vice doesn't open quite wide enough. I eventually got it off with my biggest pipe wrench, which of course marred the rubber a fair bit. The chug cap itself unscrews easily by its handle, but the base needs a heavily serrated perimeter (like a classic Nalgene bottle) or hex/octagon shape to have something to grip onto. The base gets tightened by tightening the cap, so it's all-or-nothing. It's a very shortsighted design for such a premium priced product. Functionally, the 36 oz Yeti doesn't insulate nearly as well as my smaller Hydroflask, but it's much better than a non-insulated Nalgene. Trying to contact Yeti about the issue is equally frustrating, as all their contact options lead to dead ends and even the Chat With Us link doesn't go anywhere or open anything. They utilize the contact page as a shameful means of selling more product.

I wanted to see what all the fuss was about so decided to invest in a YETI Rambler..
I will say, I love the chug cap and it's very nice to drink from, however after only a week the cap was completely jammed and stuck and I was unable to take it off. I ended up having to use a zip tie and hammer to resolve this. I found this hack by googling it and it turns out it is a common issue with this bottle which is very frustrating. I also I find this bottle incredibly heavy! The weight has surprised me with it being heavily advertised for the outdoor/camping/hiking lifestyle. Previously I have been a ride or die Hydroflask drink bottle lover and have had multiple of these over the years that I still have and cannot fault. They have no dents or scratches, much lighter in weight and keep ice for much longer than the YETI which is surprising. I have also found it to mark quite easily in comparison to other brands .. many have claimed these are indestructible so that's also been misleading. I'm glad I purchased to get it off chest but definitely would not repurchase in future

I love my Rambler 18 oz it keeps my ice coffee perfect all day, however, I've stopped using the optional plastic straw my husband purchased from Yeti. I have found that once the contents are gone if I have let it set a while and forgot to close the black sipping portion of the lid any residual drink that may be left in the straw will spit out. I've three times been showered with coffee when I went to retrieve the Rambler. I'm guessing it's due to a pressure change in the canister. I would still recommend the 18 oz, just not with the straw. I use it everywhere. It can fit inside of my small backpack and I also have a clip which attaches to my back pack and the water bottle. I love the convenience of it being small, and not as heavy as my larger yeti water bottle. It’s just right when your st the pool, quick trip to mall, and by night stand for sipping.

Overall great bottle, but cap seems to be designed to break.
The two part cap Is made out of one translucent Lexan type material, which is extremely sturdy, hard, and with a high measure of toughness (that’s an actual material science term). The second part of the cap Is made out of a much softer kind of black polymer with a large handle, but a very small thread. With time, the black part of the cap Seems to undergo what’s called creep deformation, which is the result of prolonged stress over a long period of time. In this case, it’s about 2 to 4 months. As you screw the cap on, it will slowly screw down further and further, until you eventually strip the threads all together. When you couple that with a very large handle, in comparison to the size of the thread, the amount of torque that you apply to the cap Is far greater than the thread can take. This is not caused by misalignment or user error, this is what’s called planned obsolescence. The cap is designed to eventually fail, so you would buy another one and another one every few months. I hope yeti decides to actually change the design, bottle caps are really not new technology, we know how to make them last a very long time.
By the way, if you store soda or hot coffee or tea, deformation will be accelerated.
Yeti, it’s time to send everyone a new redesigned cap for free. That would be the decent thing to do.