Dave wrote on 03/24/15 at 04:32:58:
you should buy an allen bit set for your 3/8" ratchet wrench (6mm at a minimum) - as it will allow you to keep the bit fully seated in the bolt head while you are applying lots of pressure on the ratchet...the tiny L shaped allen wrench won't allow you to apply pressure evenly.
This!
Over the years I've purchased a lot of "specialty" tools and I'd have to say the a hex set for a 3/8" drive is amongst my favorite (T-Handles too). You can get greater leverage (especially if using a breaker bar) and most importantly, you can use a torque wrench to apply the proper seating torque - this way you'll never go through these types of frozen bolt scenarios again (I know this one was by the factory - but nothing's worse then creating your own).
So let it soak, and go buy the right tools - and you'll be good to go.