I used antisieze on a used set of 02's when I installed my headers. I pulled em out after a week and replaced em with the ones that were on my car. They looked nearly brand new, so I just put some regular anti-sieze on em and screwed em in. I have been noticing my gas mileage has greatly dropped, I pulled the 02's out and they are VERY black so I know I am running rich. I can't hear any exhaust leaks, so I know that isnt my problem. I was reading in my Chiltons manual and it said to only use di-electric anti-sieze, that regular anti-sieze can hurt the sensor. Is this true?

 

I never read that about anti-seize, does it say anything (warning) on the tube of anti-seize about O2's? I used it on mine and have never had a problem. Of course the most obvious thing is your first guess, an exhaust leak.

 

I have always heard never to use 'antiseize with moly (molybdinum disulfide)' on plugs for this reason. Searching I found a recommendation to use the copper stuff sparingly, and not to get it on the first few threads so it can't creep into the chamber.

 

New AC Delco O2 sensors come with antiseize pre-applied on the threads from the factory. Not sure if it's a special kind of antiseize.

 

It's common practice put antiseize on plug and o2 threads.

 

Yup, my bosch O2's came with antiseize on the threads.

 

My Bosch o2s had antiseize on the threads as well. What type of anti-seize it is, I'm unsure of. A thin film of anit-seize will definitely make them that much easier to get out in the future.

 

I thought the package for the AC/Delco sensors indicated that they had been pre-coated with "conductive" anti-sieze compound. The biggest problem I've seen reported with using anti-sieze is people slopping it on too thick, to the point where it oozes out onto the inner sensor shield. You just need a little dab.

Using a "conductive" compound would be a bigger issue on the 93 single-wire sensors. The 4-wire sensors include ground wires for both the sensing element and the heaters.

 

Yeah mine had antisieze on em when I bought em. Its just weird to me because when I fist did my headers, i gained an average of about 1 mpg, then I changed from 100k miles AC sensors that have seen 2 header installs now, and put my old Bosch ones in, and i dropped an average of 3 mpg just from that. So I re-installed the AC ones again, and my gas mileage went back up, but it is not as good as it was at first. My car is definately running rich still, but I am almost positive I have no exhaust leaks before the 02's.

 

My O2s came with anti-sieze on them. Don't think that they would come that way if it was going to kill them.

 

I am getting ready to switch my rear O2's to see if I have a sensor problem or a cat converter problem and was wondering the same thing.

I was planning on using dielectric gel since the exhaust tubes can't be any hotter than the cylinder heads, but I wouldn't know if that was the best move.

 

Paulster, I know they all come with anti-sieze. But there is a sertian type my chilton manual said use only dielectric antisieze b/c regular antisieze can hurt your sensor. I just don't know if this is true or not.

 

It's OK if ya don't SLOP it everywhere.
BTW anti seize IS conductive.

 

I just got Permatex item#81343, rated for plugs, O2's, etc.

 

So did mine.