I just replaced my coolant in my 1996 audi a6 2.8 Quattro with the G12 but I only had one bottle so I put in a bottle of DEX COOL made by SHELL.
Originally there was the usual GREEN coolant in there. So my question is.. having the mix of G12 (one bottle) and DEX COOL (one bottle), would there be any problems with that?
And, do I need to put water in?

 

To make anti-freeze effective it is usually mixed about 50-50 with DISTILLED water.

 

YES!!! ADD WATER!!!! If you ever flush it again in the near future, try sticking to only the pink colored coolant (I believe it's the G0012 type).

 

also after getting out of the car and turningn it off, i can smell a slight heat smell, as if it is VERY slightly overheating smell...]
AND... my cars fan outside seems to be always off full speed, is that normal?