You will need
  • - penetrating lubricant or equivalent;
  • - heating element;
  • - sulfuric acid;
  • - zinc;
  • wax or plasticine.
Take brake fluid, turpentine, kerosene, oleic acid or any other penetrating lubricant of those that are at hand. The craftsmen is the most common liquid WD-40. Soak the cloth in the liquid and press it onto the stuck bolt. To improve the penetration of grease into the joint slightly postukivanie on the bolt.
To make his task easier, try to use a quality tool. Carob keys, replace the cap, use the heads. Not necessary to buy high-quality German tool for the pros. Just don't use cheap Chinese.
Loosening use the reception of the buildup. About the same, as do the drivers of the stuck cars. By the way, this method will further strengthen the penetration of the grease into the thread.
If the previous methods do not help, try to lengthen the shoulder of the key, putting him on a suitable pipe section. You can try to hit the wrench with a hammer, trying to Unscrew the bolt.
Try heating the stuck item in any suitable manner. For example, a soldering iron, a Hairdryer or a gas burner. Well heated the bolt easier to come off. You can try and quenching the hot parts, but it could backfire.
Take wax or clay and vilaite around the bolt round the wall. In the resulting capacity around the head of the fastener pour sulfuric acid and put a small amount of zinc. The resulting electroplating solution, leave for about a day, then try to Unscrew the bolt again.
If the result of all the failed efforts, the bolt will break and damage the head, do not despair. Visible remains of the details of the weld lever and keep trying. Or a suitable drill bit drill out the remains of the part of the thread.
And the next time to avoid such situations, use only high-quality fasteners. Before screwing be sure to lubricate slightly alkaline grease or vaseline with graphite powder. And don't forget about compliance with the specifications.