Here lately I've been using the purple stuff cut by 75% with water. Put in one of the disposable bottles sold in packs of five I believe. Squirt it on small areas at a time scrub with one of them HF 2-3" wide paint brushes, then rinse off with water in another spray bottle. Let dry. If I'm cleaning bare metal surfaces, do the same but take paper shop towels wipe dry followed by Starrett M-1. I banned WD-40 for rust issues in my shop. Later I coat with machine or way oil. I do not allow soap or water get near slides where it can get up between the surfaces. The only time the purple soap has been a problem is on poorly painted surfaces. It will lift the first coat off. Most of the time that is fine with me because I generally prepare the surfaces and re paint.
BTW- All good answers above including if you want to use WD-40, too.
KEn