Almost all the time a 3/8 inch tatchet with a 3 inch extension will work. If it feels like it is going to break they split by the ball which holds the socket.
Use a tool like this
http://www.autopart.com/tools/toolsmain/tool/T_2049.htm
I have various sizes of these but you will want a 3/8 square to 3/8inch or 1/2 inch drive. You don't get many but if its never been checked they are very hard to remove. Use a small screwdriver and clean out the hole before you start.
Check and make sure of size before ordering as I have 5/16,8mm,10mm,3/8. If a 3/8 inch is sloppy it will be 10mm.