W123 Steering Wheel Removal

That's overkill. Heat is used to loosen loctite, but you don't want to melt any plastic. I would take a 1/2 inch steel rod, heat one end to red, then hold it against the bolt for 30 seconds and try again. I would avoid an impact and use a 2 foot breaker bar, as the vibration could damage the shaft bearings, switches, etc if held on for long. If none of that works you can always drill the head out to get the wheel off and give you room for serious work with a stud puller or vise-grips.

As a locksmith I have pulled a lot of steering wheels but have only pulled one on my own Mercedes (1983 W123) Mine had an Allen screw retaining the wheel and what I did was to insert the long end of the Allen wrench into the screw and then two smaller wrenches to give me the leverage I needed.

Since you have a bolt or perhaps more correctly a hex head cap screw, I would use a 6 point socket, with an extension and a tee handle breaker bar. This should give you the leverage you need to break the most recalcitrant fastener. Be sure to start this process with the steering wheel locked.

I suggest the Tee handle breaker bar as an Ell handle breaker bar on the mother of a job you have requires you to push in real hard inward to keep the socket from slipping on the head of the screw while trying to apply torque with the other hand. While this can be done one slip and it is good by windshield.

I would not be afraid to use the impact to remove the allen bolt only. If you have any valve grinding compund you may want to put it between the head of the allen bit and the steering wheel bolt to keep from rounding the bolt. Mike

Impact on allen is always a bad idea... because majority of allen socket are not designed for impact. You will simply ruin the socket.

Even if you didn't ruine the socket, you risk damaging the allen bolt.