Wear gloves before dealing with them is the best way, nitrile is cheap and you can find lots of other uses for them.

After it’s on there, wipe your hands with a rag or shop towel to get any grease or liquid off works well with a dry rag, then dawn dish soap works really well. Wet hands, lather them up, doing the whole 30 second hand washing procedure will usually do it, you may want a scrub brush for under your nails. Most people that aren’t getting things off aren’t wiping off the bulk or washing their hands well, take your time to scrub it all down, and let the soap have time to get through the hydrophobic layer so you can rinse it all away.

That said sometimes you’ll stain your fingers with stuff, and you’re just stuck until that layer of skin goes away, or you eat fried chicken.

They are made to fail open now because how many thermostats have caused overheat issues. Honestly to not see one in 10 years would be hard unless you don’t do much volume of work or don’t work on engines that have coolant.