Try Kroil or PB'laster spray, soak for a while. SG is probably right, tho. Oxy-acetylene torch, heat the boss that the 02 sensor screws into, not the sensor itself. Get to dull-red all the way around boss, and un-screw. Careful, that will burn you before you touch it. Good luck.

I ran my engine on my Chevy truck four about 3 min. and than used PB Blaster let it soak for a while and had no problem getting mine out in the exhaust pipe. The one in the exhaust manifold is quite hard to remove without a torch and the proper tools and some kind of penetrating oil.

Haven't tried it myself, but this sounds like a perfect test for a penetrant spray recommended in Rick's free automotive advice. Check out the source.

You need a bottle of oxygen fluid and acetylene fluid, mix them together, light them on fire, and aim them at the bung that the sensor is screwed into.

You need a torch and an o2 sensor socket

No lubricant on earth will remove that but heat

im 1995 dodge caravan oxygen sensor has never been removed is 19 years old but when I try to take it off it's so rusted around the nut the holds it on what's the best lubricant to use to get it to loses