How can I remove an extremely tight bolt?

-I'm trying to remove the rear seats out of my 2005 Mazda 6 and in order to do that I have to remove four 10mm bolts. These bolts are absolutely impossible to get out. I really don't want to put a substance in my car thats going to stain or smell it up, any suggestions?Blowlamp with a soft flame (air nearly fully off), heat the bolt and holder from underneath the car (remove carpet and plastic from around the area)

Heat it just till the underseal starts to smoke.

Next take a 10mm socket and ratchet that's been in the freezer for 40 minutes.

Undo the bolt. - if it doesnt go after 5/10 seconds, give it a sharp tap with a small hammer, or hammer and a punch if you cant get at it with the hammer head.

Be quick.



Heat increases the size of both the bolt and hole, the ratchet then cools the bolt first and it shrinks a little in the bolt hole, comes out easier - old school engineering.
10mm bolts wont actually be that tight, but i suspect you may be trying to use an open ended spanner and it just keep slipping off, try using a socket set instead, this has the added advantage of having extensions to help get at those more awkward to reach bolts
You need leverage. Use a breaker bar (16" or 18" long handle ratchet) The long handle gives you more leverage.



Or you can find you a pipe that will slide over your wrench or ratchet, slip it over and push/pull on the pipe.. This will give you more leverage
seat bolts are made that way so they wont back out and cause an unsafe condition, like a loose seat in an accident, it just takes a long socket wrench and strengh, i use a air driven ratchet, they are not easy, thats all,
you need more leverage ,,,, get a wrench that fits the bolt properly. then get a short piece of pipe that will slide over the wrench handle , this will give you a longer handle and more leverage.
can you look under the car and see the other end of the bolts? if you can then spray pb blaster on the threads under the bolts.
Best way is to spray w/ penetrating oil. Try knocking it w/ a hammer and turn it at the same time.
cut it off or a MASSIVE hammer(joke about the hammer)