Thanks for the info. When I'm dismantling the old VWs, I use PBlaster and heat. I've heard very good stuff about Kroil's abilities.

 

PB Blaster does make some lubricants but I'm pretty sure the stuff I use is for busting loose nuts and bolts. I've had pretty good luck with it even on my 23 year old in-board boat and 30 year old Mercedes. Once in a while I do twist off a bolt head but it works much better than WD-40.
I havn't tried Kroil but I'll give it a shot when I run out of PB Blaster. I'll give the acetone/ATF solution a shot next time I have a stubborn bolt. That's an interesting approach. I was chemist for 15 years and it sounds like it would work well.
So, I didn't have any trouble pulling my original O2 sensors today (disconnecting the electrical connection was the hardest part). I sprayed them with PB Blaster Monday and let it sit until today when I gave it another squirt and then fired up the truck and drove around for 20 mins or so. I used a 10 inch cresent and they broke free with a couple of tugs.
Good luck and remember to watch out for the hot exhaust pipe.

 

For y'all wanting to try the atf/acetone mix, use a glass bottle to mix/store it in. Those same guys were talking about how it will eat through a plastic bottle. And wear rubber gloves and glasses, acetone is some nasty stuff.

 

http://www.pbblaster.com/PB_Blaster.html

PB is definitely a penetrant. I don't know if it's the best or not, but it's always done the job so whatever.

 

i had the same problem and after i rounded it off a buddy mentioned using a pipe wrench to get it out.. its a 22mm or 7/8" socket/wrench.. i broke the oem wrench from autozone mine was so froxe in place.. i rounded it all off trying to use a crecent.. so what did i di.. well i determinded it was in a retarded place so i bought a o2 bung for like 3 bucks from napa drilled a hole on other side of cat lenthaned the wires by about 6 inches(could have gotten the 18inch pigtail version for like 1 more) put it in pluged it in and 500 miles later not a hicup or miss yet....and went up 1mpg up to about 16.92mpg right now.

 

Crescent wrenches are good for scrap metal. Anyone who advises someone to use a crescent wrench for any reason should be beaten with said crescent wrench.

Using a pentrant, along with heat from a propane torch, will aid in removing the stubborn sensor. Inspect the threads on the bung to insure they aren't stripped, and if they're still good, coat the threads of the new sensor with some anti-seize.

 

A well made Crescent wrench is fine for something that big as long as you have it adjusted correctly.

 

The part in bold is an oxymoron.

 

and were in my post did i recomend using the crecent wrench.. i used it cause it was big and the o2 is in a dumb place.. and yes it rounded it off to.. a pipe wrench would have been the ticket but i dont have one... so i drilled a whole welded on a new bung screwed it in and been running great ever since.

 

Just take my word on this one. Use Coca-Cola to penetrate the rust. Its a trick an old Audi tech taught me when I was young. After it works it kinda freaks you out that you drink that stuff. It has not let me down since. Used it on an o2 sensor in my old stratus came right out. and just about anyother stuck on/ rusted on parts