Well, Rock Auto had a special on the O2 sensor for my '92 Sentra w/1.6L gas engine, so I said, "Why not? 177K it probably would not hurt."
Except I cannot remove the old sensor. I've been spraying it with Liquid Wrench for about two weeks, and I went to remove it yesterday. No dice. I have a 7/8" O2 socket, but it doesn't get a good "grip". The corners are starting to round over on the sensor.
The replacement sensor is almost spark-plug like, but the old one's flats are not as high, and it sits in another little plug (like a reducer bushing, which I presume is welded to the manifold) and there is not much room to get any kind of tool on it.
I can live without the new sensor; I just don't want to break the old one and not be able to replace it.
Any hints or tips?