WD-40 is great for cleaning, particularly threads, but also metal surfaces. It generally doesn't eat plastic, isn't a crazy skin or respiratory irritant.

I use it a ton to clean off threads of stuff exposed to the elements. Get dirt, old oil/grease, water, and any grit or rust or other things out of threads so they tighten properly and don't get jammed up with stuff.

If something I'm working on is dirty, it gets a spray of WD-40 and a rag to help not foul up the inside of whatever I'm opening.