I changed my O2 sensor yester in my car. Took about 15 minutes. Now big deal. I noticed a difference. Nothing big, but something that I can tell. I just wanted to share.

------------------
1991 Camaro RS, 305, Chevy 3.73's, Auburn Pro Posi, March Underdrive Pulleys, K&N Open Element Filtercharger,

 

I have a replacement in my car, because my current O2 sensor is bad. I think I will change it tomorrow while my engine is cold.

 

Change it while the engine is hot. The metal bung will be expanded and will let go of the O2 sensor easier than a cold one.