There is some new style wrenchs out there that grab on the flat side of bolt heads, or if ya really have to there are some special sockets out there for use on hard to get out bolts and nuts, they are tapered and clamp down when you wrench on them.. Sears has them. would probally have to replace bolts then.. otherewise are your wrenchs spreading apart as you try to loosen them, maybe week wrenchs..