Anyone have a routine / test to see if two oils are mixable? I have a DX III atf fluid mixed with Fuchs TITAN ZH 4300B (synthetic hydraulic oil). I have mixed them in a glass bottle without any settling over one month time. I belive there must be other ways to test this?

Heat them and see if the mix becomes cloudy and you might even get a baseline viscosity and see if it gets thicker over a period of say two months but tightly sealed .

What base oil is used in the Fuchs Titan ?

Carry out Demulsibility (ASTM D1401),Foam ASTM 892, and Filterability (1.2 micron)
Also carry out compatibility test by preparing 100ml samples with varying ratio mixtures at 0C, ambient, 50C and 70C for a period of 120hrs
Check samples at 24hrs, 48hrs and 120hrs for signs of separation, clarity, floc-culation, deposits or gelling.

Frank