Today while driving on the highway my coolant temp. went way up. It kept dropping to normal then back high. It mainly happened when i went over 50mph. Has anyone else had this issue?
Im still new to audis, and i was wondering if i could go to auto zone or someplace and get some g12 coolant and put it in. And can i just top it off or do i need to drain the current coolant i have. Thanks

 

You don't need to drain any coolant. you can top it off if needed. You may have a flow issue or a malfunctioning thermostat.

This is an issue with a few possibilities

 

I am going to take a wild guess here.. Does the temp stay normal at speed, but when you idle the temp goes high?? If so, the problem is your water pump. The impeller is plastic and when it cracks and breaks it wont spend at all when just idling. But at high speeds it gets enough momentum to spin the impeller. Easy to replace the water pump.