I have a 1986 240 with the original oxygen sensor which I'm replacing (generic from FCP Groton). I've seen suggestions in the archives that on a non-turbo, a box end wrench (22 mm, or 7/8") will work for removing the sensor. I tried briefly with the wrench, but there isn't much rotational range, and I wasn't sure if I'd actually got the sensor to move, or if I'd just rounded the sensor's corners.

I've also seen a horror story, that even while using a proper oxygen sensor socket, an acetylene torch still had to be resorted to for heating the manifold, in order to budge the sensor.

Should I just abandon my attempts with the box wrench, before I damage the sensor, making it harder to remove, or is it worth a try, before biting the bullet and buying the oxygen sensor socket?

Thanks, David