Have you tried the ATF/Acetone? I was a Kroil user until I mixed a batch of this stuff up. Put it up in mustard/ketchup squirt bottles from Wally's World and have converted everyone I have given it to. A couple aircraft fixers I know say it is like magic--even on aluminum and exotic metals.
RD --
Automatic Transmission Fluid is just hydraulic fluid with various
wetting agents and
deoxygenators mixed in. Until fairly recently, hydraulic fluids were basically
mineral oil. Mineral oil costs me $1/qt. Commercial hydraulic fluids (including ATF) cost a lot more. The
penetrating in P-12 systems is
oil of wintergreen which cost (circa 1995) $6/gal. I use a fair amount of acetone such that I buy it in 5 gal drums.
I ran into the ATF/acetone mix back when I was developing automotive airbag restraint systems. The problem we faced there was dendritic bonding of mated austenitic stainless steel parts (for which the
only solution is plating or making one side of the "joint" be a martensitic stainless steel). I have never tried it on corroded parts. It seems to me to be the same basic approach (just without the oil of wintergreen that promotes capillary intrusion).
I don't often have to deal with corroded joints these days. Nearly all my work is of my own design and manufacture I oversee (if not perform). As a design & development engineer, I know how to avoid setting joints up to corrode, so it is either working on old equipment or a screw-up on my part that leaves me dealing with corroded joints. I would have to go back to the mid-1970's to state that dealing with corroded joints was
common for me. I never bothered with Kroil as (A) it did not work as well as P-12 or the mixture I learned to make as an apprentice and (B) it was way to expensive for the results it gave -- at least that was my opinion in the mid-1970's.
Try adding some oil of wintergreen to your mixture. I suspect that you will like the results even better. I just thought that a
formula from the dark ages might be of interest. As you say, everybody I introduce to this stuff loves it!