Still searching but wanted some opinions on what has worked for you. My issue is a rpm related pump whine when hot. Will throw some Lubegaurd additive at it for now then change fluid then change pump in that order- have had this or that issue with my system for years. 89 chev k1500 Saginaw with hydroboost, trans cooler on this system. I am using a u-joint vs rag joint so that will contribute to some noise. I have thrown many pumps at this issue and am considering a good used GM unit now. Lived in northern Canada where keeping PS systems and hoses happy is a challenge- found Acura fluid worked very well. - on a dyno tuning session the M1 ATF blew out the pump pressure cap, what a mess. - Amsoil swelled cap seal - using Redline (with some Ford friction modifier) now with a above mentioned whine. Looking at a fluid I can buy by the liter or jug some of which are hard to source here. - LiquiMoly - Driven - CHF 202, I have had good luck with Pentosin products in the Honda manual trans. - CHF 11S - Febi/Bilstein (part number?) - Idemitsu (not liter size) - Ford XT-5 - Lubegaurd seems overly expensive even compared to the above. I think your seeing a German trend here;) So....I welcome your thoughts.