Foaming Antifreeze

[Will N]

I've experience foaming after driving at sustained high speed, which I cured by adding a capful of the anti-foaming stuff that they sell by those carpet cleaning machines that you can rent at a supermarket. I believe I have Prestone antifreeze in the radiator. How fast did you go on your test drive? If it was a fairly short drive at 30-35 mph, I would suspect as Brent suggested that there might be something else going on.