I just pulled up the msds for the main frier cleaner used by restaurants. Seems that the main component is hydroxyacetic acid...basically a form of strong vinegar. It would conceivably cause an artificially high titration. It is 100% soluable in water and boils out at 212 degrees. I dont know how one would determine before hand it its an issue. Maybe one of the forum experts can advise?
Rick, would you suggest doing the shake test on the oil, then drain the water, shake some more until the titration stops dropping to get the real titration number? I have had some oil that titrated at 15 after drying, but the acid still had no effect on. Leading me to believe that something is neutralizing the acid.