[A4] coolant issues

[f550v12 at aol.com]

All,
 
Had a coolant leak issue this weekend and wanted to get some input.  I left my car parked for two days while I was on a work-related trip and when I returned, I went to start my car and the coolant warning light came on.  Sure enough, when I popped the hood, the entire tank was empty.  It was Sunday, so the city dealerships were all closed (Audi and VW) and I couldn't pick up any G12 coolant.  I was also 45 minutes away from home, so I took a trip to Advance Auto Parts.  Of course, they don't sell G12, but three of their salespeople convinced me that I could use a new generation form of Prestone coolant that, when mixed with water, claims it is compatible in any vehicle no matter what type, and any coolant color.  Anyone know anything about this?  Am I OK driving my car for now if I use this?  Thoughts would be appreciated.