WELCOME BACK!!

Kensai, welcome back!! we saw you were off the frequency for a bit, I thought that maybe HYDRA put you on probation!! (LOL!!) Just because you werent driving, doesn't mean you can't post!!

I was reading about O2 sensors going, and causing decreased fuel mileage even though the codes aren't there. It sounds a good time to change mine, I am at 101K at least the before cat ones. If I replace it will it throw a code until the new one gets "Broken in" or should it just be plug and play?

Wonder if the bad fuel mileage is due to your IR plugs?........

^ LOL ^

No doubt Tommy!

Plug and play but you need to reset the computer so you won't get good gas mileage for the first little as seen here: Engine Code Index (Check Engine Light?)

HYDRA,

NO IR HERE. I tried the Autolite Platinum for a short time, but they werent long. I have been on Autolite Copper since Indy D and I believe you set me straight. I am thinking of changing the before CAT O2 sensors but the ones I see at least at A/Z are the ones you have to assemble the wiring, any ideas on where I can find one that is really plug and play with the connector already assembled.?

I am still here, just not checking in as often as I would like. I am pretty much in the same boat as Mean green as far as going back to school. It's about time I finish what I started and that is to get me a 4 year engineering degree. UNT Denton has a new one of a kind engineering field that deals with energy conservation. Since I had once been a HVAC A/C guy for quite a few years, I understand the energy concept.

So having a full time Information Tech job and a full family to take care of, the most spare time I can muster is just part time school. Taking just 2 classes per semester. Lucikly Uncle SAM has the lifetime learning and hope tax credit that I can fully deduct my education! Free education is better than no education! :)

Otherwise, I do respond to any messages I can relate to and can firmly give a sound answer to.

Nope, my IR plugs gave me same or slightly better mileage. I must assume (I hate assuming things) that it is because my Truck has been garage for so long, the sensors and all the other stuff may tend to gum up a little from idling fluids and what not. These IR plugs are still Champion Truck plugs as well. Took a few of them off for inspection and they are still super clean.

Keeping up with a routine full severe maintenance schedule on my D, the only thing left to check is my 02 sensors. I have replaced just about all the other sensors knowned to go out on a 1st gen durango in the 90k miles this thing had.

I do agree however, that for some funny reason, once I have changed out my fluids on my diff and tranny, and transfer case all at the same time, the first couple tanks, my MPG's improved by more than 10-15 percent. I usually avg 11-12, but during the first few hundred miles after changing out all the tranny/diff fluids, I noticed the MPG was at 12-13. Then eventually dropped back to 11-12. At first, I thought it was just coincidence. But after replacing my fluids 2 more times in the life of my Durango, both times, it temporary showed a MPG improvement.

So definitely something in the tranny, transfer case, and differentials made a temporary MPG improvement when running new fluids thru them. I just wished the improvement would last much much longer!

The only thing I could suggest is only use Fully Synthetic Fluids. They break down slower than regular lubricants. Also with the PCM learning the truck could change things back to normal.

Dang PCM... It can't be fooled like my wife:cool:

I like the OEM ones.

Hydra, you know me, I only use the highest grade materials available for my D. So if I use full synthetic Castrol Oil, you betcha I do the same for all other fluids. I am using ATF+4 so that is 100 percent synthetic, but not sure about the gear oil.

Also would not know how or why the PCM would relearn things just by changing fluids on the tranny and axles unless there are sensors that say "lookie lookie, new clean fluids"