I use only 100% VG juice with my eGo-C attys and tanks with no problem. Just remember that gravity is your friend in terms of keeping the juice in contact with the wick, so try to keep it in a more vertical orientation (battery end down) when you're not actually drawing on it. In terms of avoiding leaking, from my experience the most important thing is to use a soft draw when vaping because the strong suction of a hard drag seems to pull more juice through the wick than the coil can handle.