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What really happens to the MD-X if you DON'T buy premium gas and go for the 87 octane regular unleaded?
 

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What happens?

Your MDX will EXPLODE!...heheheh kidding...NOTHING WILL happen. It will run fine...Bunt since it is an ULEV(Ultra Lowe Emmissions Vehicle) I recommend using the highest octane for engine quietness, performance, and corrosion prevention within the valves, PGMI and headers and exhaust.
 

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Use Search

There have been many discussions (and some experimenting) regarding gas grades. Use the searh feature to dig up these old threads. Good luck.
 

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sgbingham said:
What really happens to the MD-X if you DON'T buy premium gas and go for the 87 octane regular unleaded?
Hey the difference between 87 and 91+ octane is only $70 a year for something you just have or will pay $40K for. Don't you think champagne would be more suitable than Pabst Blue Ribbon! ;) BTW, there's an octane sensor on the X that retards the spark with lower octane so you may save some money but you will accelerate more slowly. As msu suggested, there are numerous threads we folks in the Class of 2001 discussed and analyzed the heck out of this issue so do some research if you want to learn more.
 

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Ironically, if the spark is retarding to avoid detonation, there is a darn good chance the efficiency of the engine is reduced and your mileage will be slightly worse. So you have saved virtually nothing.

But the difference in price between 87 and 91 is usually quite large. Even so, you would be splitting hairs I think on any savings. I would go for the champagne!
But remember, quality and octane of gas are not the same thing.

The reason the timing is adjusted by the engine management system, is in case you can not get the octane you need in a certain locale.
 

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I suspect that the 91 "requirement" is for two reasons -- to get the highest possible mpg (which is helped by advanced ignition timing), and to minimize pollution (ditto).
 

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DaleB said:
Ironically, if the spark is retarding to avoid detonation, there is a darn good chance the efficiency of the engine is reduced and your mileage will be slightly worse. So you have saved virtually nothing.
There may be a difference in mileage, but I don't think anyone has claimed it is as much as 20%. It certainly hasn't been for me (more like 5%, if at all). However, the difference between 87 and 91 octane is 20% around here, so it definitely isn't a wash. As long as I'm not operating in a 'severe' environment (towing, etc.), I would rather save $100/year and put it on better oil and other things that Big Red needs.
- Conrad
 

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Re: The price of gas

Come on people gas is cheap! Compared to last year how can anyone complain? When adjusted for inflation EVEN last years prices was cheap!!

The price for gasoline in my area today is actually cheaper than what I was paying in 1979!! Does anyone remember what they paid for a loaf of bread in 1979? or a gallon of milk in 1979?

Granted I too am all for saving money whenever and whereever it makes sense for me to do so. But saving tens on cents on a gallon of gas in a luxury/performance SUV costing $40K is not one of those areas in my mind.

Acura said use 91+: I can't imagine not doing so to "save" a few bucks. By the way 20 cents a gallon translates to about $3 on an average fillup. Which translates to $150 per year assuming about one fillup a week. Is it really worth it?
 

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An article I read on a Toyota Highlander suggested that lower octane while commuting around town was fine, but use the 91 for your highway driving, towing, or generally when really pushing the car.
That might be a reasonable compromise as long as you remember what's in your tank when you hit the road.



_________________________
Second 'X' Test Drive Sat with checkbook in my pocket.
 

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I was using 87 for the first 3 months then I decided to go with the 91 (got paranoid). Turned out that mpg went from 17 to 19.5 around town. Your milage may vary. We were consistantly 17 and now we are consistantly 19.5. So I feel it is a wash and I don't have to be paranoid.
 

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Come on People Use Super

If you can afford to purchase or lease a MDX, you can afford to use the recommeded higher octane gas. It is better for the engine internally, and will get you better mileage. You can damage the engine by using lower or cheaper gases, especially because it is an ultra low emissions type vehicle. If you afford the gas I think you should sell or trade your MDX for a Saturn, Kia or an Hundai!!!!!!!!!:D
 

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I agree with using a higher-octane gas. Actually it may not make a big difference on the short run, just a little difference in the mileage. But on the long run, it has a great effect on the engine.
The Octane number has some thing to do with the detonation timing or the duration of power cycle. The higher the octane number, the higher the duration of combustion. So most higher quality engines (i.e. used in German cars and other luxury cars) will have a higher stroke than standard engines. the engine size can be simply calculated as follows:
Engine Volume = n.D.S
Where n= number of cylinders
D= piston diameter
S= cylinder stroke
Since increasing the piston diameter has a limit and involves some complications at larger bores, a lot of manufacturers tend to increase the stroke to increase the engine capacity and therefore the torque. But this doesn't come for free. The longer strokes require longer combustion timing so that the power cycles will not loose the pushing power until the piston is at the top of the cylinder. In this case, using a lower octane gas will go the job specially when you don’t need a lot of torque, but think about it this way. During the power cycle, the combustion will loose the pushing power before it gets to the top of the cylinder and continue moving by the momentum. But if you need a lot of torque the piston may not get to the top easily, which affects the electronic system controlling the valves and the other mechanical components. Specially with the VTEC system, it may be critical.
So, if loading the X with big people, towing a boat or go uphill a lot, you need to consider using the 91 Octane. Otherwise, you may be affecting the life of your engine.

BTW, in San Jose, California, I noticed that some time last year the Octane numbers changed. The 91 became 90, 89 became 88 and 87 became 86. Does anyone know why?
 

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The grades went down a point due to Federally-mandated additives to reduce emmissions.
 

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Don't you just love a government that's too dictatorial for the taxpayers' good? Federally-mandated, my foot! Vote the buggers out of office if you don't like the laws they're passing!
 

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Doesn't the 2002 Honda Odyssey have the same 3.5 liter Vtec engine as the MDX? I heard that it also offers 240HP same as in the MDX... But the gas required is regular unleaded, not premium unleaded. Why????

I also heard that the new Honda Pilot suv will also have a 3.5 liter engine that requires only regular unleaded gas.

My salesman did say its ok to use reg. unleaded in the X.
 

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Today, I checked with the service dept. and was told that all they use in their MDX loaners is REGULAR UNLEADED. Also, the Honda Odyssey and Honda Pilot will be getting the same engine as the one in the MDX.

Has anyone received this same info. from their service dept.? Maybe, we should all check this info. (this could save us all some $$$)

I was told that the car's computer will adjust for the lower octane and that no harm will be done to the engine.

Are there any Honda engine engineers to collaborate this info.?
 

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I am not a 'Honda' engineer, but I can tell you all modern vehicles can adjust to some degree to compensate for the availability of the recommended octane requirement.
That does not mean they are running at their most efficient level. That octane level is what's printed in your owner's manual, and was based on the engine design and it's use within that particular vehicle.
If they later found it could be run efficiently on regular, with virtually no loss in power or mileage, then they should put out a technical service bulletin.
 

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Recommended not Required

It is OK to use whatever grade you want to use - check the manual! However the manual plainly states that it is recommended you use an octane of 91 or higher. The engine will compensate for a lower octane, but the engine IS compensating!!
There will be a loss of performance, how noticiable is probably highly variable due to differing sets of circumstances, but there will be a loss of performance. The engines were designed to operate that way.
 
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