I only clean my machines with sewing machine oil. If there is rust on metal parts, then Bar Keepers works.
I don't take machines apart to clean unless it a total must do to get machine working correctly. That said, I have never taken any of my machines totally apart to clean them; sections yes, entire machine no. Somehow with a good bathing in sewing oil and many wipe with cottonballs and q-tips, a machine gets clean. Hard to move parts gets Tri Flow ( Thank you Cathy for showing me this product).
I once followed directions to clean with GoJo non-pumice, only to have decals silver and disappear on me. I was pissed when that happened. I NO longer use that stuff.
In my many wanderings of google searches on cleaning vintage sewing machines, I came across one blog were that blogger only cleaned with sewing machine oil. He had the most gorgeous machines I have ever seen (wish I had bookmarked his blog, cause I can't find it now). He stated it would sometimes take him weeks to remove layers of old oil and dirt that had layered up. The decals on his machines were pristine. That sold me on just using sewing oil to clean these poor ladies and gents.
MUVs cleaning is what I would follow if I were a newbie to cleaning vintage machines and I was totally scared of what if...