what kind of anti-frezze goes in 2001 jetta vr6

The green polyethylene glycol should be fine use pre- diluted or a 50-50 water to coolant ratio, unless you live somewhere that gets very, very cold, like 40 below, the use maybe 70-30. Use distilled water, it has no minerals that can contribute to corrosion. I looked at some other websites and can find no reference that demands it use the red coolant

Oh yeah, I forgot, as to the overheating, change thermostat, forget about testing it they are not expensive. Make sure fan is working, and come on back and let me (us) know if that helped

What kind of anti-freeze is in it now? Green is a common type. Red or orange is for longer life. Sometimes the two don't mix so buy the correct type. Use a 50-50 mix for the best results.

With the aluminum heads and cast iron blocks in the VW engines, the extended life (orange) or Pink stuff from VW is ALWAYS preferrable...and probably required for warranty issues. Also, after replacing thermostat and verifying fan and hose serviceability, you can also add a product called Wate Wetter to further remove gas bubbles from the coolant to improve thermal transfer.

The Jetta has a cast iron block and aluminum heads? OK I learned something there...I believe you Scott, it just seems the temperature changes would not expand and contract at the same rate and cause problems, but I guess the engineers use an alloy for that.

It's not the expansion/contraction rates that's the issue. When dissimilar metals are bonded, it creates a weak electrical potential that causes galvanic current. This can result in galvanic corrosion which introduces acidic particles into the coolant. This was especially problematic on the Vanagons with watercooled engines...they were magnesium alloy blocks with aluminum heads. The extended life coolant and the pink stuff have extra additives to combat these corrosive contaminants.

This article is very accurate: http://en.wikipedia.org/wiki/VR6_engine

Right on man. Thanks for the education, really-

VW nerds rule.