When bleeding brakes and the new fluid is the same colour
 

as the old, how do you know when the old fluid is out?

Sounds like you are changing it fairly frequently (a good practice) and hence no color changes. There really isn't a lot fluid in the lines from master cylinder to the calipers. I remove the old fluid out the master cylinder with a Mityvac and fill it with new then start. So rough guess from past jobs, 4-5 ounces for the rears and 3-4 for the fronts (all per side) to clear the old and run with the new fluid.

I use a quart and it gets all the old out. When i used Super Blue, I would alternate it with the amber colored and a quart would ensure the old was out. plus it's not like you can really save an opened can of brake fluid (so I'm told) so I just used the whole quart.

I used to measure the volume when I went from Blue to gold (or back). In my 1973 it took about 150 ml to flush the farthest caliper. If you do about a liter equally divided, you will get the old stuff out.

it depends on what color he started with.

as said,, you need to remove the old fluid from the reservoir before putting in new.

+1 on cycling an entire quart/liter thru the system. I did this initially and now alternate colors to simplify things.

Thanks guys, will go through the whole container.

Food color added to brake fluid ??
 

Bad idea. The food color is water based. Water and brake fluid are not a good thing. Anything the end user would put in brake fluid is going to adversely affect the fluid performance.

Doing the farthest first (LR on 911) showed me that it takes the most so I do about .35L on it followed by .2L on RR. Then .35 on RF and last bit on LF. I learned this back when Superblue was common. Bet I’ve done thousands of cars...

Excellent,

Thank you for the good advice . . . and I thought I came up with a novel idea . . . ha ha.

Regards,

How do know you're using 0.35 or 0.2?

Our machines reservoir is clear and has four distinct lines. Pretty easy to eyeball from a distance.