Has a rep as one of the finest tranny additives.
As far as solvents go, anything that is strong enough to really work in 15 minutes is probably too strong for comfort. Mine, anyway.
Auto-rx actually cleans. The metal surfaces are shiney after treatment. I was especially impressed with the nature of the material I found in the filter pleats after the 800 mile treatment: small, hard, what appeared to be carboniferous specs. Gritty. May be from the ring area. I would like that gone if it were there.
Not a lot of sludge-type gunk as the engine was pretty clean to begin with... But a bunch of stuff I wouldn't want in my motor. The oil was darker than it usually is after a total of 2,500 miles. I'll be putting in another 16 oz. in about 2K miles for a second 800 mile treatment: it will be interesting to see what THAT filter looks like when it is cut open.
'91 420 SEL @ 199K, '92 SVX @ 181K, '93 SC400 @ 86K, '93 Kaw ZX-11 @ 30K, '87 F250 @ 181K , 2001 Valkyrie Interstate @ 6K, Y2K Honda NightHawk 250 with 1.5K, '88 420SEL I.@ 179K & the 2nd latest, an '88 420SEL II.@ 210K runnin' parts car, '85 F150 300/NP435