And current-day car thermostats. If it fails, your engine overheats, and that's an expensive repair. If you ever see a high temp warning light on your car, you can take it out and test its functionality in a pot of hot water (or replace it for ~$20)

Also, was how the lunar rover handled cooling. Big block of wax used as a radiator. Well, not radiator exactly!

I don't think the LM used wax for thermal management, but the Lunar Roving Vehicle did, as a "thermal capacitor" [1]. That is, heat was stored in a block of wax while driving, and then radiated away between uses.

[1] https://en.wikipedia.org/wiki/Lunar_Roving_Vehicle#Wheels_an...

That’s what I said. Lunar rover.