He meant to pump suck out brake oil in the reservoir pump and fill in fresh fluid without bleeding all 4 calipers.

Eventually the new fluid will mix with the old fluid along the lines. Repeat this step after a couple thousand km to continue mixing the new and old fluid. Eventually, those old fluid will be replaced out.

Anyway, I prefer to bleed out the old fluid and replace it all with fresh fluid. Mechanics doesn't charge much for this service anyway.

This post has been edited by Thrust: Mar 24 2020, 10:42 AM

I don't use this method. I'll just send the car to a mechanic and ask him to do a complete flush and bleed the caliper.

Probably should do it once every two years.