Anti Freeze turned brown.

It is rust buildup in the motor. Add a little detergent (Dawn) to the mix and go drive for a week. The pressure and antifoaming agents in the coolant keep it from sudsing.

Drain, rinse, repeat. Now, one thing you should look for...make sure that the coolant you're adding is not (at least for the time being) silicate-free.

What is silicate? Well, it's sand. Really fine sand. In the old days, silicates were used to "scrub" the system and remove water deposits, and rust. It's handy for doing that now, although it takes awhile. Coolant for aluminum engines (and I'll assume most modern coolants) typically does not have silicates, but I honestly have not checked lately (I run GO-5 in all my stuff).

You need something to break up the surface tension and scrub the crap out, and punching the block drains wouldn't hurt either. You're going to have to drive it, long term, to get it all cleaned out. Period.