A flathead screwdriver helps. If it’s so cold that the plastic’s brittle, then what are you going to run in the radiator, and what’ll you do for tires?
It was about 45 degrees in my garage the other day when I had to open a new bottle. Had a race on Sunday and needed to mix up a couple of gal. I was using a screw driver to pull out the cap and it wouldn’t pop out, the cap came off without turning it!! About hit myself in the chin! I guess I need to use a heat gun!