Did he stop the engine as soon as he heard the knocking? Did he lose ALL of his oil (red dash light on continuously) either through a hole in the sump or hitting a brick in the road? Has the problem been building up slowly over the past weeks?
There is a product called Ametech Engine Restorer and Lubricant that contains millions of tiny CSL copper silver lead spherical particles (2micron dia) that can rebuild bad crakshaft main bearings IF YOU CATCH IT QUICK enough. If the shell bearings have become so worn they have rotated on the crank then it is too late and the engine has to be stripped down and examined (or swapped for a good cheap take-out engine)
http://www.AmericanTechnology.co.uk
is a good place to start. Good luck
Donald Bergandi
January 2009