Quote Originally Posted by iCake View Post
I'd personally say it a bit different though. На (этих) выходных поеду к дедушке...
Oh, I forgot this case.

George1992

Note the difference between "на выходные" and "на выходных".
"на выходные" = "for the whole weekend". It is "for the period of time".
"на выходных" = "in some (maybe not known yet) moment of time during weekend". This is the same as "в" in the examples above!
Grammatical case rules the role of the word in the sentence here.