in my experience with bleeding brakes, no matter what fluid is used, the most common problem with not being able to get all the air out of the system [not counting upside down calipers] comes from guys pumping the living wizz out of the pedal before cracking the bleeder. this will cause foaming of the fluid. if a guy just lightly pushes down, open the bleeder, close the bleeder, release the pedal, no foaming happens. rinse and repeat a couple of times, done. if by yourself, lightly crack bleeder, put a tight fitting hose on the bleeder, then submerge the hose into a jar or can with clean fluid. lightly stroke pedal, rince, repeat several times per wheel, done. this has worked for me for many, many, years.