For example caliper piston boots and CV joint boots. I don't want to clean them with something that will ruin the rubber's life.

My caliper piston boots have never been cleaned and got some brake lube on it that I'm not sure is safe for rubber (nothing on the packaging mentioned rubber).

One of my CV joint boots is also has a lot of oil that leaked on it from engine.

Is there special cleaners for these things? And is there supposed to be a rubber protector that you are supposed to apply after cleaning?

 

Some silicone based lubes are made for brake parts and might even help preserve the rubber components creating a barrier that slows/prevents oxidation. I use SilGlyde. Anything you clean, you can put a thin coat on it to protect it from the elements.

As far as cleaning greasy stuff that won't damage.......

Mechanics mostly use brake parts cleaner spray. Not sure what it does to rubber though.

My preference is Simple Green HD Pro. They sell it by the gallon and you dilute it to the desired strength in a spray bottle. More Eco friendly as well. It is also recommended for cleaning food surfaces.

https://simplegreen.com/products/pro...ner-degreaser/

 

I use Dawn dishwashing liquid to clean some parts, including rubber parts. It dissolves grease very well.
of course it also washes clean with ample water.

Dawn right out of the bottle also makes a dandy lube for installing rubber parts. It will wash off while driving through a rain storm.