The 2 are not compatible and should be completely drained to include the heater core. Then replace it with the green antifreeze as there is a class action suit against General Motors regarding Dexcool.
The car will over heat.
Probably a blown head gasket. Get a technician to look at it. If it is, it will be a major ordeal.
It depends on if you see the antifreeze leaking or it is just disappearing. If it is just disappearing then a bad head gasket or cracked head may be the problem. The smoking could actually be vaporized antifreeze. If that is the case don't run it until you can get it fixed.
the heater core could be stopped up, or could be low of antifreeze, or the thermostat could be stuck open
Nothing Nothing
the heater core may be plugged up
there might be a leak some where in a coolant line. or maybe you have a leak in your radiator.
Volkswagen or any other vehicle shouldn't use any antifreeze. If any car is using antifreeze something is wrong.
heater core has a pinhole leak! Only shows when under pressure .remove and replace not good to breath antifreeze vapers!
probably a blown head gasket.
heatercore leaking! also change thermastat.
It could possibly be the thermostat or the cooling fan. Let the engine warm up and when it gets to 232 to 235 degrees the cooling fan should come on. If not you need to go from there.