The drain cap is a push and rotate style. Plastic with little hooks around lugs that I have to push and rotate at the same time. I've had it off before after other trips and in spring when I flushed the antifreeze. I'm in high desert in the Oregon and we get freezing temps and harsh winters.
Here is a pic of the tool I referenced earlier. Someone left it in a campsite 10 years ago for me. It works great for unhooking fittings with new gaskets that make them tight.
It has been very useful over the years.