Engine cleaning advise needed.
I'll second the crockpot method. I've used it for numerous mufflers and cylinder heads, I turn the temp on low and let the engine parts sit in it for 24 hours and if there's any castor stains left, they come off if you brush it off with a cloth.
Try it, I bet it works better than any other item listed. Plus antifreeze is available everywhere unlike z-best engine cleaner.
Kris.