Is it safe to mix different octane gases ,in the same tank?
I currently have regular in my Cobalt and I have about a 1/4 of a tank, but my next fill up will be V-Power Premium, is it same to mix them like that, or should I run it till its dry then fill up?

 

you'll be fine, but the mix will dilute the octane rating a little bit. but shouldn't have any problems.