whose, mine or tsuami's?

 

A heavy foot equals lower mpg, bottom line get your foot out of your...throttle.
Air up your tires to 40 psi, roll up the windows and turn on the a/c, take the roof rack off, remove the extra weight in the back, and drive slower!!
I drive mixed, 16 miles one way to work, half city half expressway and I average highy 14's and low 15's in mpg.

 

I don't use anything more than 87 octane at 6400 ft because it is useless. I'm sapped 30% of my power from the altitude to begin with with a nat aspirated engine.
The only vehicles that get anything over 87 octane in our family is the B5 S4 Twin Turbo that can take advantage of the dense air/fuel mix and this little econo bucket as well. http://www.discovery-automotive.com/...oject_betanoir
Most guys/gals with a big block and a carb on their speed boat up here on Lake Tahoe run 87 octane as well. With no EFI to compensate for the altitude the gas that takes a more volatile mix to explode isn't worth the extra $$.
Our Land Rover runs perfect on 87 octane the S4 on the other hand(as well as the WRX I sold) Pings like crazy with anything less than 91 octane.
If you follow the address above we run that little car on 110 unleaded from the local(and only) Sunoco dealer that sells it in 50 gallon drums out by the CAT HOUSES ;_)
On a side note my B-Berry took a dump on me so until the big brown truck shows up I'm down from instantly answering/asking questions.

 

Any idea on the cost to fix O2 sensors?

 

For a DII they are around $70 a piece, replaced in pairs. If you can crawl under your truck and turn a wrench you can change them. DI's are a bit more $$.

 

Just a FYI-LR's require premium gas because their engines do not have a EGR (exhaust gas recirculation) and the purpose of the EGR is to lower combustion temps by sending a small amount of exahust gas back into the engine to be burned.
By lowering the combustions temps it reduces emissions.
87 octane burns hotter than 91 octane.
91 octane burns cooler, more completly and has more BTU than 87 octane gas.
So even though you dont get the spark knock from the lower octane gas that you would (you actually wouldnt because of the knock sensor) at sea level you are getting a incomplete combustion and running high combustion chamber temps and polluting more.
A engine designed to run on premium will get lower MPG with regular.
With the higher combustion temps you will greatly reduce the life of your headgaskets and exhaust valves.
And you will shorten the life of your cat's because they are having to work harder to do their job.
So that $5 that you are saving once a week at the gas station will cost you 1 billion dollars in a few years.

 

more like 3.7 trillion

 

Well that's a much better explanation than the Red Rider B.B. Gun answer floating around here AKA "You'll Shoot Your Eye Out !!!. I run the equivalent of one container of B99(a few times a year) with a full tank of fuel. Most of the EFI cleaner on the market is some variant of diesel fuel anyhow. This keeps my internals clean. I've gotten answers else were but no mention of the lack of an EGR on the 4.0 engine(chock something else up on my vehicle knowledge list). I'M GOING TO WRITE OUT A CHECK FOR 1 BILLION+3.7 TRILLION AND HANG IT IN MY OFFICE SO I KNOW HOW MUCH I"M SAVING BY RUNNING 87 OCTANE ;_) I'm honestly on track to fill the D II up 30 times in a year I work out of my house. I'm going to ask my local Rover guru what octane he recommends for Tahoe He's a straight off the boat UK transplant so he knows his stuff.
I'm going to order a shop and owners manual this weekend when I got the truck home I realized that I had a owners manual for a 1999 4.6HSE after about 100 miles away from were we bought the D II. I can't go any further without a quick reference this has been a few months now with no manual of any sorts for my D II SE 4.0 ...UGH!!

 

Up until a year or so ago, I could still buy 93 octane here in Denver and let me tell you, it does make a big difference even at altitude, more then a mile a gallon and a lot more low end torque.

 

how often should the O2 sensors be done? I'm now at 74k miles and I dont think theyve ever been changed. Is it every 60k miles? Also there are 4 right? Are they about $70 each through a good aftermarket like AB? Changing them looks simple, just unscrew and unplug right?