i use a brass bristled brush and a mixture of "bar keepers friend" and water.
and a good bit of elbow grease.......
wd-40 works well too, but still use a brass bristled brush.
they also sell brass brush attachments to go in grinders and drills.
the trick with those is to use low RPMs.
i will not use brillo pads.
i will not use steel wool.
they both will dull the shine of chrome.