Ron:

I'm not sure of the editorials roots, However it looks like the company serves the aftermarket or repair industry. I am sure that it has a slant toward the seller of parts. However everything published these days seem to be biased and self serving in some regard ( except my stuff, cause I'm just a shade tree mechanic with no affiliation with the automotive world. To my testament, my most recently retired car was a Corvette I had for 14 years, that I drove almost daily, and still sold it for almost what I had paid for it. ). I preach synthetic oil and correct air pressure in tires, and cant believe that a tranmission is "filled for life"

I have also seen other articles which concur with the one I hyperlinked. Do a "google" for O2 replacement interval, or or O2 Sensor repair and you will find other information. I believe the Bosch and Denso sites also have information. When I moved to Florida, we used to have emissions testing ( it was based on county, rural counties were exempt ). But here in the Miami / Fort Lauderdlale / Plalm Beach area we were hit hard every year. They got rid of the silly program when they realized that the passing rate was 99.99% for vehicles MFG after 1996 (the vast majority of the vehicles). So the state scrapped that waste of tax dollars. A friend had two older vehicles (late 80's / early 90's, a chevy and a caddy ) that failed the test and O2 sensors fixed the vehicles so that they passed the test on the next try. I think the fact is that most people dont keep cars to near the 100k mark anymore. My neighbors and frends almost all lease vehicles for 2-3 years and therefore hardly even change the oil, let alone other parts. It's funny, they can't even comprehend the concept of repairing (or even cleaning for that matter) your own car. Being that I have replaced almost every other electrical sensor in the car, I just figured WTF. And the fact that I was able to get all 4 sensors for just $80.00 more than the dealership wanted for one I figured , my luck, I would need one in a few weeks and be screwed buying one at the dealer. I replaced the MAS at about 89000 miles, it had no CEL, but was extremely sluggish and althouth gas milage on the higway was fine, the car just didnt feel right. I located a MAS online for under 150.00 in the sealed box and in under 5 minutes it was replaced, the difference was amazing. It was like installing a new engine. I would reather do preventvive maintenence at my leisure and price than to get caught needing a dealer part or service at a dealer price. I really like my ML despite its past problems. I intend to keep the ML till it gets a catastrophic failure (engine/tranny) and then toss it off for junk or a charity vice fixing. However I would probably purchase another ML if mine died tomorrow, although the wife likes the look of the BMW X5 and X3. My basis for keeping a vehicle is as follows. As long as I can keep a vehicle in good condition, with no dents, shiny paint and all item functioning as designed for about 1/3 of what the car payment was per month or less, (excluding gas or insurance) then I am money ahead vice buying a new vehicle. I feel that I have gotten my moneys worth since I have had the ML since new (nov 97). When I got the ML and started having the usual ?? problems, I wasn't so sure. The last straw was almost when the harmonic balancer exploded at around 40K miles at 80 MPH on the turnpike, the car filled with oil smoke. I told my wife that I thought the perfect second car for us would be a roll back truck to haul the ML around. However it seems to have gotten better with age.