I have a 2009 touareg v6 with 215k miles that I got from my sister In law. They bought it in 2016 and put a little over 90k on it. They are the kind of people who do not maintain their vehicles, so I have no idea what the maintenance records for this car is. That being said, it's in decent shape. However, the coolant is very low, I cant even see it in the res. I'm planning on doing a flush, but since vw requires such specific coolant, should I use any flush additives? Or just stick with water and new coolant? Any tips for a first time VW owner?