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Ok... with over 11k on the clock now, my 2003 is averaging about 18.5 mpg... that's about 70% highway, and I must admit I found no difference in octanes, so I burn regular (for the moment, until gas is reasonable again).

There was no "10k computer adjustment" as some have mentioned noticable
 

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I have had similar experience:

2002 MDX - no roof rack

9600 miles - 18.7 primarily 93 Octane

50/50 highway / city

New England weather did not dramatically impact mileage.
 

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Where I live in CT most stations have 87-89-93. If you go to a large station they generally have 87-89-91-93 and some will also have 88. The two local station by me have 87-89-93. When I can find it I use 91.
 

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I guess in the eastern coast, we see 87, 89, and 93 in most gas stations. I could find some 92 octane in same other gas station as well. I believe in New Jersey, there is 94 or 95 octane gasoline as well.
 

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I do not own a MDX yet, but am considering one. Do these things require you run Premium unleaded (91/93) or can you run lower octane without any problems?
 

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Good idea to investigate this before you buy!

This topic has been discussed quite a bit. The owners manual specifies 91. Yes you can use a lower Octane. My rule of thumb - the engineers at Acura designed the engine for optimal performance on 91 - I bought the MDX and want the full benefit of the engine power that I paid for - therefore I use 91.

I moved from a 95 Accord that got 28 MPG on 87, yes it is more painful to put 91 in a vehicle that get 18.5 MPG but I new that going into my purchase decision and I can afford to pay for both the higher octane and the lower MPG.

Good luck on your decision.
 

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A Good Thread To Read On This Topic

timbrwolf9 said:
I do not own a MDX yet, but am considering one. Do these things require you run Premium unleaded (91/93) or can you run lower octane without any problems?
An often discussed topic here. Many owners have reported using 89 or even 87 octane with no negative results. The owners manual says to use 91 octane or you can use regular with possible reduced performance.

If you have some time read this thread. A long and heated discussion on the same topic:

http://www.acuramdx.org/forums/showthread.php?s=&threadid=10194&highlight=regular+or+premium
 

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I dont understand why regular or premium gas is such a big deal for new car buyers.

Lets say you burn 20 gallons a week and the difference between regular and premium is .15 cents, thats $3/week or a big $150 a year extra for premium gas.

Is this really a concern when your car just cost you $40,000?????
 

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zubinh said:
I dont understand why regular or premium gas is such a big deal for new car buyers.

Lets say you burn 20 gallons a week and the difference between regular and premium is .15 cents, thats $3/week or a big $150 a year extra for premium gas.

Is this really a concern when your car just cost you $40,000?????
Here's another way to look at it. The difference between regular and premium is now on average .20 cents. At 20 gallons a week, over the life of the vehicle, say 10 years, thats over $2000!

Anyway, here's another article on Premium vs. Regular:
Using premium gas doesn't make much difference
 

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Arzoo said:


Here's another way to look at it. The difference between regular and premium is now on average .20 cents. At 20 gallons a week, over the life of the vehicle, say 10 years, thats over $2000!

Anyway, here's another article on Premium vs. Regular:
Using premium gas doesn't make much difference
That article is not really relevant to the MDX engine design, and as it points out, using premium fuel will not make a difference for "most" users.

The MDX is a high compression engine with variable valve timing to assist in a usable torque curve, good power output on demand and to control emissions. If you use a low octane fuel, the system will sense the pre-ignition (ping) that results when using a low octane fuel in a high compression engine (especially in a wide throttle position) and will retard the valve timing. The engine should run fine, but with reduced torque and power output. Further, I don't know what the engineers had in mind, but suffice it to say that I would not think the design included the possibility of running long term with a retarded valve timing/cam position. Whether running the engine in a retarded spark condition for the long term is going to affect valve timing component wear, camshaft wear, etc, remains to be seen.
 

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norcalchuck said:


That article is not really relevant to the MDX engine design, and as it points out, using premium fuel will not make a difference for "most" users.

The article states: Running regular fuel in an engine designed to use premium does reduce performance and fuel economy, Furey said, but too slightly for most drivers to notice.
I run on regular and I can't notice any difference. As for damage to the engine, Acura only recommends Premium fuel, it's not required. We all have a choice. :)
 

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My mileage is disappointing...

to say the least. I'm doing mostly "city" driving, lots of stop and go traffic. But the best I can do is 15.5mpg on 93 octane, and that includes short (5-10 mile) highway trips, too. Any suggestions?
 

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kgbmom,

15.5 mpg using 93 octane in the City is pretty good. Try switching to Regular gas and I bet you will experience the same mileage and performance. At least you will be saving money at the pump.:4:
 

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Really??

What about all the other guys here at MDX.org who practically disowned me when I asked if I could use less than 93 octane?? They really scared me out of trying Regular gas!!
 

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kgbmom,

There are a good number of members that use regular gas in there MDX's, including myself. It comes down to your personal choice in fuel octane. Give regular gas a try for a period of time, not just one tank. Then, you can come to your own conclusions. Good luck.:29:
 

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Arzoo said:


The article states: Running regular fuel in an engine designed to use premium does reduce performance and fuel economy, Furey said, but too slightly for most drivers to notice.
I run on regular and I can't notice any difference. As for damage to the engine, Acura only recommends Premium fuel, it's not required. We all have a choice. :)
What he said.:4:
 

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norcalchuck said:


Further, I don't know what the engineers had in mind, but suffice it to say that I would not think the design included the possibility of running long term with a retarded valve timing/cam position. Whether running the engine in a retarded spark condition for the long term is going to affect valve timing component wear, camshaft wear, etc, remains to be seen.
Interesting perspective. But I do not believe there is such a thing as having the optimum octane rating at every single fill up, Therefore, I would think the spark condition and valve timing would often be in a state of some degree of retardation, as small a deviation as that would be.
I also would not think the mechanism would be such as to be in a 'strained' conditon if the fuel rating is not 91 or above, as to cause undue wear on any engine components. It would simply work over a range.
Now, will some detonation be missed by the knock sensors thereby increasing some load on the engine? I don't think it's likely, but maybe a slightly greater possibility than the former.
I have been running 89 for sometime now, and am tempted to try a tank of 87. But the weather has been mild, and I am not towing anything. Performance has been excellent, as always, and mileage seems the same. Hot days, towing, etc. I would probably run 91. This is all by the 'seat of my pants' but many years of driving many different vehicles. Including ones that acted like the brakes were dragging after switching fuels.
 

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EXCALIBUR said:
kgbmom,

15.5 mpg using 93 octane in the City is pretty good. Try switching to Regular gas and I bet you will experience the same mileage and performance. At least you will be saving money at the pump.:4:
Note also that at least here in the West, the refineries switch over to oxygenated fuels (was MTBE now ethanol) in the fall and switch back in the spring. The estimates I have seen are that oxygenated fuels result in about 4% lower fuel economy, so perhaps the miserable gas mileage will improve soon by maybe 0.5-0.7 MPG. I am lucky to get 13.6 or so in purely city driving, short runs, hills. The trip computer showed about 22MPG on the flats in I-80, but after a run through Donner Pass to Tahoe, the whole tank averaged out to about 18.6. Guess Honda has done a good job of keeping the rolling resistance down, but it's a heavy vehicle (4300 lbs plus passengers, plus gear) and every time you brake, you waste tons of kinetic energy. I don't know where they got a 17 MPG estimate for city. I do note that in the fine print on the Monroney (window sticker)sticker, below the MPG rating, the fines print says " Actual mileage will vary with options, driving conditions, driving habits, yada yada......", and then goes on to say that city will be between 14 and 20 and 19 and 27 on the highway. Obviously they averaged the two numbers for city and came up with 17. I actually didn't pay attention to that when shopping. One of the reasons I bought the MDX was to stay away from the gas guzzling behemoths such as Chevy Tahoe, Ford Expedition, etc, (not the Ford Excursion however since you must always under California law use chains if snow controls have been imposed--the AWD/4WD exemption only applies to vehicles under 7000 lbs) , but I don't know that the city mileage is much different.
 
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