The question posed involved a difficult to remove sensor.  The advice
being offered is for just that situation.

A normal wrench is fine most of the time, but . . .

Karl Wolz

> WOW. Where do all of you people LIVE?!?
> I recently had to remove 2 oxygen sensors from a pair of 87's- one had
> been sitting in a field of tall grass for years, and the other was
> driven in the snow all the time. I used whatever wrench it is that
fits
> (7/8"?) and just... unscrewed them. No penetrant, heat, or anything.
>
> Amazed,
> Simon