I use a clear tube attached to the bleeder screw. You can see the difference in new/old fluid as it moves through the tube. Added benny to the clear tube, you can see any air bubbles as they push out with the fluid.

__________________
Mike Tangas
'73 280SEL 4.5 (9/72)- RIP
Only 8,173 units built from 5/71 thru 11/72

'02 CLK320 Cabriolet - wifey's mid-life crisis

2012 VW Jetta Sportwagon TDI...at least its a diesel

Non illegitemae carborundum.