My GFs 02' A4 car has 32k on the clock. Bone stock, daily driver. It is in need of a fluid/filter change. What all is entailed in the flush systems that the dealers have? From what I understand, it forces out the old fluid, and recovers it, and then pumps in clean fluid, correct?
Could I rig something up with my air compresser? I was thinking, apply a pressure regulator to get the PSI a lot lower, around 15psi or so, and hook it to one of the lines. Do I risk any internal damage doing this? Is it even possible? What line would I need to apply pressure to, and where would it drain from?
Or am I just thinking crazy?

 

or disconnect the return line, put it in a bucket... start car, and constantly pour clean fluid in dipstick tube as its being pumped out.

repeat until fluid pumped out is a nice clean bright red.

 

I have done the above it work but you better have alotta fluid on hand and a large funnel , But you should also change the filter too , Honestly though with all the mess and fluid and such Im not sure you would save any money over just having it done.