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socalJD said:


Hmmm, let me get this straight. You called AHC and spoke to a CS rep just to support your opinion. I imagine the call went like this:

AHC: Good Afternoon. Please be advised that this phone conversation may be recorded to assist in customer service and future training for American Honda employees . . .

You: Hi, I need your help. Please give me some expert information to refute this guy on an internet chat site that I belong to who doesn't buy into my opinions.

AHC: I'll be glad to sir, what seems to be the problem.

You: Well this guy is saying that the MDX & Pilot have the same engine, and the only reason Acura is saying to use premium gas is to promote their upscale brand image.

AHC: Sir, I will have to consult our technical group since this is a specific question for which I don't have the usual canned, scripted, customer service response . . . please hold. (wave music playing in the background)

You: (thinking to self) I'll show that smooty know-it-all to never question my unqualified, unsupported personal opinions again.

AHC: Sir, after consulting the technical group, I can asure you that Acura would surely never do such a thing. Your superbly engineered and crafted MDX engine differs in so many ways from the Honda Pilot & Odyssey engines. For instance . . .

You get the drift. Congratulations. You win. I would blindly and wholeheartedly believe everything that I hear from a 3rd party telemarketing group contracted by AHC over the phone. What was I thinking ??? :rolleyes:
Thanks for proving my point without a shred of doubt. Welcome to the club of "I have a Ph.D. in Automotive Engineering from MIT" and Acura engineers are liars :) Makes me wonder why you are buying cars from such glib people. With your script writing skills, you must've won a few oscars by now. Go buy a Porsche or something.

Like many others are saying, this is not a question of which octane to use - that's a stupid question. Its the inherent nature of some people to challenge facts without any education in the matter whatsoever. Hey, there's internet - who needs degrees. I'll Google my way to nirvana :2: Its asinine that people don't read comments and come back to the "right octane" issue. This is my last response - bark away at how you can run MDX on sewage water or diet Coke....
 
This is entertaining to say the least. So let me put my two cents in on what I've read in the past few pages.

Ronsully said:
I wonder if a compression test or leak down test would show any damage with the 87 octane users.:D
I doubt there'd be any difference if you drove the same with premium or regular unleaded. The amount of deposits left on the piston, valves, and combustion chamber have much more to do with driving style and quality of gas used. Chevron is arguably the best quality gas out there. Their Techron additive is in my opinion the best one of all the gasolines. And unlike Shell...they put this additve in all three grades. So if you used Chevron, no matter the grade...you'd have less deposts than if you had been tanking up at Arco all this time. Also...someone who is doing full throttle pulls on a regular basis isn't going to have many carbon desposits vs. someone who drives like there's an egg under the throttle. Ever see that initial poof of black smoke from the back of a car when someone gives it the whip? That's carbon built up in the combustion chamber goign bye bye.

socalJD said:
One can argue that the MDX engine is tuned slightly different to justify the extra 10HP, but I doubt it - probably has more to do with the improved exhaust system.
You could argue if you want...but you'd lose that one. While the motors are mechanically the same, the ECU in the MDX is programmed to allow more timing advance, giving more power...because they are assuming that since you had the coin for a luxury brand vehicle (ok...near luxury), you've got the money to afford the expensive gas too.

Ronsully said:
Gas Mileage has nothing to do with octane and everything to do with pre-ignition.


Does everyone at least agree with the above statement?
That's somewhat true. Octane and fuel mileage can be related. But mileage is also dependant on the engine making a clean burn. If detonation or pinging occurs...the computer will retard timing. Retarding the timing lowers the efficiency of the combustion of the fuel charge, which in turn reduces fuel economy. But...by using a higher octane, you can counteract the possibility of pre-ignition. And if there's no pre-ignition, the computer will allow the most efficient timing curve, which in turn gives you better mileage.

frainc said:
Since SuperTech works at Acura, I believe he knows this engine alot better than most of us. And if he tells you that it will not harm this motor, then so be it.
I'm telling you that you won't damage the motor. And even if it does blow up, how could I ever prove that it was bad gas that blew it up if I ever wanted to balk at a warranty claim? Unless you fill the tank with half diesel, water, or anything other than gasoline...as long as the knock sensor is working, you probably won't catastrophicly damage your engine with the gas you use.

My final words on this matter, to answer the topic of this thread...no it's not a must. It's recommended.

My own personal opinion? I would use premium anyways. You did in fact pay more for the Acura version of the Pilot. One of the differences is more power. You can really only take advantage of that power by using premium (unless the air temps are really cool where you live). Why not take advantage of it? Otherwise...you're complaining about having to a few extra bucks here and there for gas, yet you had no problem paying several thousands more for the Acura tuned engine over the Honda. And that to me is petty.

I'm aware that some of you are technically savvy enthusiats, engineers, or whatever...and your minds can't be changed because no matter what anyone else says, you believe they are wrong since they lack the analytical ability and degrees on the wall you have and they're nuts to doubt you because you've figured it all out. I've gone up against these types before, and it's just hilarious to me that anyone would still doubt what a professional mehanic who knows theory of operation, technical specifications, diagnosis, and repair of their car better than they think they do. So if any of you care to disagree with what I've said, other than the personal opinion in the last paragraph...go ahead and post it. I'll just rebut every post with simply this... :21:
 
I had to respond again because of SuperTech's great reply. I couldn't have it said it better if my life depended on it :) Great job!
 
Some are very good at making assumptions with no knowledge or references, whether they be from Google or a text book at home.

No one said acura engineers are stupid, etc. But has anyone actually talked to one on the subject at hand?

No one ever suggested running the MDX on anything but pump gasoline, so you folks who find it necessary to exaggerate to make a point, can stop.

Thanks ST for throwing in your automotive expertise in the mixture, and adding clarity to the final blend. :)
 
DaleB said:


I'm glad it didn't !!

:D

I'm glad too :4: since the same thing said another way by SuperTech tasted so sweet, didn't it? Cut and dry observations are difficult to digest.
 
SuperTech said:
I doubt there'd be any difference if you drove the same with premium or regular unleaded. The amount of deposits left on the piston, valves, and combustion chamber have much more to do with driving style and quality of gas used. Chevron is arguably the best quality gas out there. Their Techron additive is in my opinion the best one of all the gasolines. And unlike Shell...they put this additve in all three grades. So if you used Chevron, no matter the grade...you'd have less deposts than if you had been tanking up at Arco all this time. Also...someone who is doing full throttle pulls on a regular basis isn't going to have many carbon desposits vs. someone who drives like there's an egg under the throttle. Ever see that initial poof of black smoke from the back of a car when someone gives it the whip? That's carbon built up in the combustion chamber goign bye bye.
I just had to make a comment about this. You are speaking of detergents in gas. I am speaking about octane. Compression test/leak down test will show you if the motor is hurt from detonation among other things. Also, the poof of black smoke may not be carbon build up. If the smoke is blueish it could be oil burning. Black smoke to me could also mean running rich or a burnt valve.
 
Ronsully said:


I just had to make a comment about this. You are speaking of detergents in gas. I am speaking about octane. Compression test/leak down test will show you if the motor is hurt from detonation among other things. Also, the poof of black smoke may not be carbon build up. If the smoke is blueish it could be oil burning. Black smoke to me could also mean running rich or a burnt valve.
I think ST was just adding some info with regards to the small discussion on engine deposits one poster was asking about. It hardly takes away from the crux of the discussion.
 
OK, if everyone is going to agree with Supertech then maybe his response should be posted as a sticky in the FAQ section so that a new premium gas thread is not started every week.........
 
JL_SS said:
OK, if everyone is going to agree with Supertech then maybe his response should be posted as a sticky in the FAQ section so that a new premium gas thread is not started every week.........
Yes.. very good idea..
 
Ronsully said:


I just had to make a comment about this. You are speaking of detergents in gas. I am speaking about octane. Compression test/leak down test will show you if the motor is hurt from detonation among other things. Also, the poof of black smoke may not be carbon build up. If the smoke is blueish it could be oil burning. Black smoke to me could also mean running rich or a burnt valve.
I warned you...

:21: :21: :21:

Everything you need to know was in my last post. You didn't quote it, but here. Let me quote the part that you need to study more.

SuperTech said:
as long as the knock sensor is working, you probably won't catastrophicly damage your engine with the gas you use.
Forget compression tests, smoke, or burning oil. The knock sensor is the key here. It allows you to "get away with" any octane you want. If your knock sensor does not work (most common cause for failure, believe it or not, is that the single wire that goes to it under the intake manifold gets chewed by rodents), then the check engine light will be on, the computer will default to a failsafe fuel/timing curve to avoid damage, and you'll be having that taken care of at the dealer in hopefully short time. But...since it DOES work, it will do what it's supposed to and prevent any damage from occuring by detonation.

Now you could theorize that driving like a grandma could build up carbon on the piston, valves, and combustion chamber...enough so that it can effectively raise the compression ratio. Higher compression ratio = more chance of detenation. Assuming you didn't change your driving style, you'd keep building up carbon, and keep needing more octane to avoid pinging and the knock sensor intervening to pull timing back. Eventually, the carbon would build up so much that the compression ratio would be so high, that even Av Gas, and the knock sensor retarding timing to the limit still couldn't avoid detenation and then you have the damage resulting from constant detonation that you keep implying will happen. Sure...it's possible. But this would take a process of several hundred thousand miles (I doubt any of you will keep your MDX that long), and the head gaskets would probably blow from the increased compression long before the computer just absolutely can not retard anymore timing.

In other words, as I said...you will not damage the engine from deviating from the recommended octane fuel. Deposits can clog things or build up in places...and they can cause damage. But the octane itself...that's what the knock sensor is for. Think of it as an "octane detector" if you want.
 
A relevant article on testing was done by Car and Driver magazine on Regular vs Premium topic. Although this article was done in Nov 2001, the results are still valid today.

Partial summary from this article reads as follows:

"Cheapskates burning regular in cars designed to run on premium fuel can expect to trim performance by about the same percent they save at the pump. If the car is sufficiently new and sophisticated, it may not suffer any ill effects, but all such skinflints should be ready to switch back to premium at the first sign of knock or other drivability woes."

Read on... and then make your own choice.

http://www.caranddriver.com/article.asp?section_id=4&article_id=3604&page_number=1

In my case, $3 per tank difference (approximately .15x20gal), which amounts to approximately $144 per year, is cheap insurance that allows my MDX to perform at the peak performance level when needed.

I will be better off making up this $3 per tank weekly difference by reducing my food intake, which is better for my health anyway. :)
 
mgmdx said:
I will be better off making up this $3 per tank weekly difference by reducing my food intake, which is better for my health anyway. :)
Cheesecake, gasoline, cheesecake, gasoline...decisions, decisions, decisions.;)
 
I'll still take the Miller Lite over 91. The X may not run as smoothly but I will.
 
mgmdx said:
A relevant article on testing done by Car and Driver magazine on Regular vs Premium topic. Although this article was done in Nov 2001, the results are still valid today.

Partial summary from this article reads as follows:

"Cheapskates burning regular in cars designed to run on premium fuel can expect to trim performance by about the same percent they save at the pump. If the car is sufficiently new and sophisticated, it may not suffer any ill effects, but all such skinflints should be ready to switch back to premium at the first sign of knock or other drivability woes."

Read on... and then make your own choice.

http://www.caranddriver.com/article.asp?section_id=4&article_id=3604&page_number=1

In my case, $3 per tank difference (approximately .15x20gal), which amounts to approximately $144 per year, is cheap insurance that allows my MDX to perform at the peak performance level when needed.

I will be better off making up this $3 per tank weekly difference by reducing my food intake, which is better for my health anyway. :)
My point exactly. Spend a little and get some preventative maintance.
 
harmonr1 said:
...I get exactly 20.1 mpg and have to fill up every other day. The mpg is surprisingly consistent and I've checked it with the trip computer, actual fill-ups using the odometer, and over several fill-ups. It currently costs about $48 to fill it up with 1/8 of a tank left.

As an experiment, I'm going to use premium (don't know the octane rating here in CA but probably 93) and test my gas mileage. I'll post the results as well as any noticeable power differences going through the mountain pass. A week should be enough as gas topped $3/gal yesterday. Also, I have always used Chevron exclusively so I will be able to rule out any brand differences. I just hope my bank account can stomach the test!
And the results are in...(drum roll please)...After switching to Chevron Premium (91 octane it turns out), the mileage stayed exactly the same at 20.1 mpg. As far as increased performance, it's hard to say. It might have felt a little zippier when passing but it could have been just as much mental (knowing that I have premium gas instead of regular so it should be zippier) as a real sensation. But nontheless, the change in grade had no difference on the mpg. Just my 2 cents. But keep the debaye going...and friendly...as it's been very educational.:4:
 
After reading this thread, I decided to switch to regular unleaded from premium for a couple of tanks to see what would happen. I can't wait to switch back. The loss of performance sucks and I find myself with the gas pedal on the floor a lot more often to try to compensate. That might explain the decrease of fuel economy from 16.1 to 14.9. I do have 22's, so I'm thinking I need that extra octane to get those wheels going. So, it's back to premium for me.
 
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