It took less than a minute to get the bolt head a dull red using the cutting head of an oxy/acetylene torch. But I still needed to use a 5' piece of pipe over the breaker bar to get it loose.

 

when I couldn't remove my axle nut and broke a few breaker bars I went to sears and upgraded to 3/4" drive and I came off. But they didn't have metric so hopefully there is sae size that matches your needs.
update: sears doesn't carry "small" 3/4 drive sockets I had to order off ebay, 19mm or 3/4in 3/4 drive impact socket(short is better)

 

All I can say is WOW! I feel likevI have been beaten buy a flipping Toy of an engine! I have done just about all that I can short of getting the car in the air which it looks like will be the only way that it will come off! I heated that Sob Cherry Red at least 5 times. I borrowed my neighbers heavy duty electric impact gun thinking my SnapOn gun didn't have enough consistant air and the same results followed! I have to say that this is the first time that I got beat buy a bolt! Looks like I'm going to have to bring it someplace with a lift and have them do it. Nyone know what this job goes for on average in the tristate area of the North East?

 

how about having a shop break the bolt loose for you then you take it home and do the rest?