how can i unlock a 8hp brigs and stratton that ran out of oil?

Is she completely seized ? If you havn't done so already, you may have to dismantle the engine to see what exactly has seized,..piston in the bore, or crank bearing.
I had one recently, that seems like it was seized , we jiggled about at trying to rotate the flywheel back and forward, it eventually came free and the engine would turn again although a bit noisily. We were unclear as to why she was getting jammed. We took it to pieces ( crank out, head off) and found that the piston and bore was badly scored and gouged ) I'm in the midst of figuring out if a rebore and oversize piston will fix it !!.

John G
April 2010