The stuff that found that gets really jacked up are mainly in my medical kit. Stuff like mole skin (for blisters) and lip balm type stuff. The small tubes of Chapstick brand does alot better than generic brands do. The generic brand lip balm turns in to goo, but Chapstick tends to hold its shape much better and is usable.

Batteries are another thing that the heat really screws up. I don't keep spare flashlight batteries in my car kit any more.

I have to cycle the water I keep in my vehicles every week in the summer.

We are pushing 111 degrees today outside so the inside of my car is insanely hot. Fun stuff.