Frank
Couldn't get on-line yesterday, our IT personnel installed some new patches Wednesday nite - create 2 problems for everyone they fix. good way to ensure job security
As far as I know Kleentek or any other filtering system, electrostatic or physical doesn't remove soluble additives such as amine or ZDTP. However, if you have polar sludge, the polar alkyl amines will coat the sludge and thus be removed from the oil when the sludge is removed.
Trib. Trans. 47 pp.111-122, 2004 Yano,Watanabe, Miyazaki, Tsuchiza and Yamamoto, "Study on Sludge Formation during the Oxidation Process of Turbine Oils" ran 20 different turbine oils with dry TOST at 90 and 120C, pulled samples at set time intervals, ran RBOT and sludge (couldn't find pore size). Two oils had ZDTP. Rest phenol and/or amine based. Oil C had RBOT 350 hours, ZDTP, 1400 S and 59 ppm Zn. Oil F had 595 RBOT hours, 600 S and 59 ppm Zn. Authors stated ZDTP had poor sludge resistance - exceeding their sludge parameters when RBOT life was still 70%. They found sludge was primarily Zn sulfate. Oils C and F sound similar to yours and their research would help explain why Zn levels drop with usage - not sure why your sulfur went up. Would think alkyl amines would be attracted to Zn containing sludge.
I am still puzzled as to why ZDTP would be used in turbine oils but stand corrected.