| NGM_MDX |
Anyone here use gas other than premium? Was just wondering if there would be any knocking if I use gas lower than 91 octane.
I was told that 2007 MDX has a pretty high compressing ratio and should only use premium gas. Can someone explain to me the intriguing connection between compression ratio and premium gas?
Thanks in advance! |
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| G. COLTON |
This will be a really oversimplified explanation.
Think of compression as a force that is trying to make a specific volume of gasoline vapor smaller. The higher the force the smaller it is trying to make that volume of gasoline. Also as the gasoline vapor occupies a smaller volume it heats up. When it reaches a specific temperature it will try to burn, or fire. If this time is before that time designed into your automobile you get pre-detonation. This is not good for your engine as all of the mechanical components are not properly aligned.
The octane of gasoline is a rating of how well the gasoline resists this pre-detonation. The higher the octane the more the gasoline resists. Chemicals are added to the gasoline to achieve higher octane.
In your Acura MDX the computer is designed to recognize pre-detonation and correct the timing so that predotanation either does not occur or it occurs insuch a way that it is no problem.
I do not know about your 2007, but my 2004 runs on regular octane with no problems.
G |
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| srtbeem |
I would HIGHLY recommend NOT using regular in the 07. The compression ratio on the 07 is now a very high 11 to 1.
2007 sport/ent
nimbus grey/ebony |
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| shootist |
Octane ratings have been beaten to death on this forum. You can use lower octane ratings in the 07 MDX, but your performance will decrease. WIll you notice it? I do- if I run 87-89, it feels like the AC has kicked on and is dragging the engine down.
THe MDX has a very sophisticated engine managements system that monitors knock. If the engine starts knocking from low octane gas, the ignition and fuel/air mixtures are adjusted to lower performance and stop the knocking.
Knocking is bad, It wrecks an engine, and there is no going back. The owners manual says in two places, you can use 87 in an emergency, but if you do the engine and emissions systems may be damaged. |
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| renov8r |
http://www.chevron.com/products/pro...orgas/8_q-a/#13
Even they, who stand a lot of money from people buying 'more octance than is needed' almost totally downplay the idea of harm coming from goinf 'under octane'.
I have to think that driving style is a factor in all cases.
I know that when I hook up all my sensors to my admitedly old (1987) turbo charged fuel injected vehicle there is never any knock detected at part throttle/low load acceleration. COntrast that to full throtle heavily loaded accleeration and , with too much booast and not good enough fuel, I have blown the head gasket out....
Another way to look at it is 20 cents a gallon is the pretty much the same as dropping MPG from 18 MPG to 16... |
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| mesalum |
It it worth saving a few bucks?
The gas tank on the MDX is 21 gallons. The price differential from Regular octane to Premium oction gas is typically in the range of 15 - 20 cents. So worse case at 20 cents you end up spending $4.20 more per fill up by using Premium gas. If you can afford the $40k vehicle can you not afford Premium gas?
That's just the way I look at it. |
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| gurneyeagle |
quote:
Originally posted by mesalum
It it worth saving a few bucks?
The gas tank on the MDX is 21 gallons. The price differential from Regular octane to Premium oction gas is typically in the range of 15 - 20 cents. So worse case at 20 cents you end up spending $4.20 more per fill up by using Premium gas. If you can afford the $40k vehicle can you not afford Premium gas?
That's just the way I look at it.
Yea, it's called "common sense".
gurney |
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| sigp228 |
quote:
Originally posted by mesalum
It it worth saving a few bucks?
The gas tank on the MDX is 21 gallons. The price differential from Regular octane to Premium oction gas is typically in the range of 15 - 20 cents. So worse case at 20 cents you end up spending $4.20 more per fill up by using Premium gas. If you can afford the $40k vehicle can you not afford Premium gas?
That's just the way I look at it.
And its always 15-20 cents above the regular price so if we get another one of those gas hikes, know that the price will always be 20 cents more.
I figure average fill up 17 gallons. Cost per fill up extra 3.40
Average fill ups per month. 4. Cost 13.60
Overal cost for premium for a year 163.00
Paying that amount to keep my 300 horses in my 46000 dollar car..........priceless.
And if you use the Hess card or the Citibank Drivers edge card, you get some of that back.
Plus right now, average gas is 2.35 down here. Going premium accounts for an 8.5 percent increase in gas cost. If gas goes up to say 3.00 a gallon, then going to premium (assuming the pricing structure stays) then it would be a 6.5 percent increase. |
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| NGM_MDX |
| Sweet, thanks for the explanations. I actually learned something today! |
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| JeffK |
Dear Shootist:
You posted:
"The owners manual says in two places, you can use 87 in an emergency, but if you do the engine and emissions systems may be damaged."
I agree with G. Colton and there have been numerous posts on this subject.
Would you please be so kind as to give the page number in the owner's manual where it says that using 87 octane may damage the engine and emissions system.
JeffK |
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| columbiaman |
| How about if you mix half 89 and half 93 to get 91 octane. Does that work? |
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| acuramdx300 |
| I would VERY HIGHLY suggest using premium gas only. I think I read a story about a person wo had an 07 X, and he filled regular, and his engine wouldnt start one time. Unless you want that to happen to you, use premium! |
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| dj-mdx2 |
quote:
Originally posted by acuramdx300
I would VERY HIGHLY suggest using premium gas only. I think I read a story about a person wo had an 07 X, and he filled regular, and his engine wouldnt start one time. Unless you want that to happen to you, use premium!
This is just hearsay - not borne out of the experience of many motorists. Don't believe everything you read, including these posts. In the end, as long as you use clean fuel from a reliable source and you're not running a racecar engine that actually will not run unless you use high octane fuel, you're good to go. |
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| dj-mdx2 |
quote:
Originally posted by columbiaman
How about if you mix half 89 and half 93 to get 91 octane. Does that work?
Why would you? This is already what's happening in the fuel mixer at the pump station when you use mid-grade. |
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| theseans |
Shootist is absolutely right. This has been beaten to death, for whatever reason. Parcimonious natures come to mind
My 2 cents, if you can't hear the pinging after a half a tank of 89, then you're either unqualified to comment, or you're simply hearing what you want to hear. I hear it loud and clear, and I'm no mechanic. |
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| JeffK |
Before you use Shootist as a reference, remember Shootist is the person who posted:
"The owners manual says in two places, you can use 87 in an emergency, but if you do the engine and emissions systems may be damaged"
I found this statement to be highly suspect. Back in February I requested that Shootist give us the page number of the manual that contained this dire warning.
60 days later, still waiting for the page number!
JeffK |
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| Squishy |
It all depends on how you drive it and how gas prices are set in your area. If you drive it hard, the knock sensor won't be able to help you and you'll get knocking. In that case, bump up the octane until knocking goes away. Mileage will decrease with 87/89 octane, as the knock sensor will retard timing, which in turn decreases the amount of power you get out of that fuel. You should do the math and see if it really is in fact cheaper to fill up with 87 or 89.
And don't knock (edit: wahaha, pun intended :D ) columbiaman's method - in some areas, there is so much difference in the price of 89 and 93 that you can do some mixing and end up paying less than what 91 is marked at. |
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| mindmachine |
Jeffk
I don't know where shootist found his info but I posted before where the manual talks about engine damage last month and I posted the page number!!!!
Don't get me started again, but this was posted before and you responded. I don't know about two places but for me one place is enough I don't need to be told again.
What they say is:
"regular may be used temporarily. The long term use of regular may cause engine damage."
This is on page 316 in my 07 MDX Owners manual. |
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| mindmachine |
Actually here is the whole section in the manual on page 316 word for word:
Your vehicle is designed to operate
on premium unleaded gasoline with a
pump octane of 91 or higher. If this
octane grade is unavailable, regular
unleaded gasoline with a pump
octane of 87 or higher may be used
temporarily. The use of regular
unleaded gasoline can cause metallic
knocking noises in the engine and
will result in decreased engine
performance. The long-term use of
regular-grade gasoline can lead to
engine damage. |
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| theseans |
Hey Jeff...just agreeing with his point that this has been debated to death (and he has been awfully sageful in the past on some other matters). On the statement in the manual though, we differ completely in opinion. I don't fear severe damage from running 87 octane in any regular unleaded combustion engine. It's the North American standard for engines, and it's built in North America.
I would however, question anyone that cannot hear or feel the difference between 87 and 94. It's night and day to your ears, and through the pedal. I would also question anyone that can't taste the difference between moon-shine, and good scotch.
Bottom-line, both will get you good and drunk, but one will be easier on your stomach the next day.
quote:
Originally posted by JeffK
Before you use Shootist as a reference, remember Shootist is the person who posted:
"The owners manual says in two places, you can use 87 in an emergency, but if you do the engine and emissions systems may be damaged"
I found this statement to be highly suspect. Back in February I requested that Shootist give us the page number of the manual that contained this dire warning.
60 days later, still waiting for the page number!
JeffK
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| dj-mdx2 |
quote:
Originally posted by mindmachine
Actually here is the whole section in the manual on page 316 word for word:
Your vehicle is designed to operate
on premium unleaded gasoline with a
pump octane of 91 or higher. If this
octane grade is unavailable, regular
unleaded gasoline with a pump
octane of 87 or higher may be used
temporarily. The use of regular
unleaded gasoline can cause metallic
knocking noises in the engine and
will result in decreased engine
performance. The long-term use of
regular-grade gasoline can lead to
engine damage.
Nuff said. Agree that this has been debated ad nauseam. Octane issue may not be an issue (pun intended) to those who lease but maybe so for those of us that intend to drive the vehicle to the ground. |
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| theseans |
Dj...you're absolutely right. I keep forgetting the lease-crowd. Explains why this question keeps coming up. I'll wake up now.
What I still don't understand is a certain Senior Members repeated support of low octane. Ironically, a wonderful understanding of pre-detonation, yet inability to actually hear it from his own engine. I hear it loud and clear every time I suck back a half-a-tank of 89, and both of our engines came from the same place at the same time? Is climate a factor perhaps? -)
quote:
Originally posted by dj-mdx2
Nuff said. Agree that this has been debated ad nauseam. Octane issue may not be an issue (pun intended) to those who lease but maybe so for those of us that intend to drive the vehicle to the ground.
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| JeffK |
Climate is certainly a factor!
If you look at my posts, you will note that I have said, that in the summer, when it is hotter out, you may have to go to higher octane.
Cold air is denser and this permits the use of lower octane.
Also altitude: If you are in the western states, such as Colorado, the highest octane available is 89!
So altitude, temperature and humidity all play a factor.
BTW, in my '06, now that the temperature has gone above 70, I am starting to hear pinging, while in the winter I never heard it all.
Next tank I will try 89 and see what happens.
JeffK |
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| theseans |
This is interesting. I'll run a tank of 87 next winter, and see if it runs any smoother.
quote:
Originally posted by JeffK
Climate is certainly a factor!
If you look at my posts, you will note that I have said, that in the summer, when it is hotter out, you may have to go to higher octane.
Cold air is denser and this permits the use of lower octane.
Also altitude: If you are in the western states, such as Colorado, the highest octane available is 89!
So altitude, temperature and humidity all play a factor.
BTW, in my '06, now that the temperature has gone above 70, I am starting to hear pinging, while in the winter I never heard it all.
Next tank I will try 89 and see what happens.
JeffK
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| Squishy |
| Driving style also plays a factor. I can run 87 all year 'round in Toronto without any issues, but only if I keep the RPMs way down low. |
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| theseans |
Squish, you mean at low idle/ rpm, you can't hear the pings, or feel the sluggishness like when you step on it. Trust me though, it's happening all the time. It doesn't just appear at 6000 rpm. But thats fine...It will run "fine" with 87, but it will run like a champion with higher octane. If you're ok with fine, then go for it. Unlike the supposed quote in the manual, I don't think it severely damages anything. Just makes it run rough. If thats not an issue, and you're not a "car-guy" that really cares about those things, than go for it.
quote:
Originally posted by Squishy
Driving style also plays a factor. I can run 87 all year 'round in Toronto without any issues, but only if I keep the RPMs way down low.
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| Squishy |
| The knock sensor should be able to do its job and retard timing enough to prevent knock at low engine speeds. I've worked on the car before with the hood open and engine running, and there are no abnormal noises at all coming from it at idle. I've had two used oil analyses done on the car, and they show no elevated wear particles with 87 use. It appears that it's only at high RPMs that the knock sensor can't keep up. |
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| theseans |
sensors only engage when they detect something first. That means it's happening (at least enough to engage the computer)?
squish, as i said earliar, I have no fear that your engine runs without damage on 87...I use the occasional tank of it too you know. My ears and pedal just aren't in denial about the differences in how it runs on both. I would never expect metal filings in your crank. I just know they run like %@#$, or to paraphrase you, @#$% at high rpms.
So my question is....what compells you to fill your tank with something that makes your car knock and ping at high rpm? Guys who know things about cars (which you do), don't usually fill their tanks with 87. This isn't LA, we can still occasionally get our cars out of 2nd gear. Just curious.
quote:
Originally posted by Squishy
The knock sensor should be able to do its job and retard timing enough to prevent knock at low engine speeds. I've worked on the car before with the hood open and engine running, and there are no abnormal noises at all coming from it at idle. I've had two used oil analyses done on the car, and they show no elevated wear particles with 87 use. It appears that it's only at high RPMs that the knock sensor can't keep up.
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| theseans |
just reread my post....not implying that you are in denial. You at least acknowledge you hear it at high rpm. There are some other senior guys out there in complete denial, like it's some Bush Government conspiracy to make them spend more on gas. -)
quote:
Originally posted by theseans
sensors only engage when they detect something first. That means it's happening (at least enough to engage the computer)?
squish, as i said earliar, I have no fear that your engine runs without damage on 87...I use the occasional tank of it too you know. My ears and pedal just aren't in denial about the differences in how it runs on both. I would never expect metal filings in your crank. I just know they run like %@#$, or to paraphrase you, @#$% at high rpms.
So my question is....what compells you to fill your tank with something that makes your car knock and ping at high rpm? Guys who know things about cars (which you do), don't usually fill their tanks with 87. This isn't LA, we can still occasionally get our cars out of 2nd gear. Just curious.
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| Squishy |
GAS PRICES! :mad:
With the price difference between 87 and 91, I come out ahead even with the mileage drop. Plus having 87 in there makes sure I drive like a granny, further increasing my mileage. |
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| theseans |
hearing you....
quote:
Originally posted by Squishy
GAS PRICES! :mad:
With the price difference between 87 and 91, I come out ahead even with the mileage drop. Plus having 87 in there makes sure I drive like a granny, further increasing my mileage.
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| cjdoors |
Funny thing - I just took delivery of my 07 MDX over the weekend and the dealer specifically told me that IN CALIFORNIA, I could use regular gas without any problem - something to do with our gas - outside the state, use premium. I had read a professional review of the 07 prior to buying that stated when they tried to sneak in a tank of mid-grade, there was noticeable knock. As such, I grilled the dealer when they told me that and a second person on their "Acura Customer Experience" team verified it. When told my car was ready to go with a full tank of gas - I sarcastically asked if it was regular and they said it was for sure!
At some point, I'll see what a tank of premium does here in CA.
JL |
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| theseans |
I knew it!! Everything is better in the West! -) Did he mention if there were additives, etc., that make the difference?
quote:
Originally posted by cjdoors
Funny thing - I just took delivery of my 07 MDX over the weekend and the dealer specifically told me that IN CALIFORNIA, I could use regular gas without any problem - something to do with our gas - outside the state, use premium. I had read a professional review of the 07 prior to buying that stated when they tried to sneak in a tank of mid-grade, there was noticeable knock. As such, I grilled the dealer when they told me that and a second person on their "Acura Customer Experience" team verified it. When told my car was ready to go with a full tank of gas - I sarcastically asked if it was regular and they said it was for sure!
At some point, I'll see what a tank of premium does here in CA.
JL
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| dj-mdx2 |
quote:
Originally posted by cjdoors
Funny thing - I just took delivery of my 07 MDX over the weekend and the dealer specifically told me that IN CALIFORNIA, I could use regular gas without any problem - something to do with our gas - outside the state, use premium. I had read a professional review of the 07 prior to buying that stated when they tried to sneak in a tank of mid-grade, there was noticeable knock. As such, I grilled the dealer when they told me that and a second person on their "Acura Customer Experience" team verified it. When told my car was ready to go with a full tank of gas - I sarcastically asked if it was regular and they said it was for sure!
At some point, I'll see what a tank of premium does here in CA.
JL
I find it hard to believe that a dealer would tell you that. Can you get it in writing? (Fat chance). |
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| cjdoors |
| I was surprised too. I'll see if I can get an e-mail confirmation out of them and post it if I do. |
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| Squishy |
| Maybe it's because of your E10. Ethanol will raise the octane of your fuel, but I had always assumed that lesser octane gasoline was used in blending. |
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| MikeDx |
Never really thought of it (have MDX for year+)...
I have to say I agree with all of you (87 and 93), thus every single comment (or most) is correct, even the one about “conspiracy”…(only thought of it now):
Even if you only know 5th grade math, here’s proportion:
If 87x is $3, then 93x is what $? (3*93)/87 = $3.2
Thus mpg is the same!!!
So why not all gas 93 AND cheaper?
Answer: so people learn to drive less with better mpg cars. |
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| dj-mdx2 |
quote:
Originally posted by MikeDx
Never really thought of it (have MDX for year+)...
I have to say I agree with all of you (87 and 93), thus every single comment (or most) is correct, even the one about “conspiracy”…(only thought of it now):
Even if you only know 5th grade math, here’s proportion:
If 87x is $3, then 93x is what $? (3*93)/87 = $3.2
Thus mpg is the same!!!
So why not all gas 93 AND cheaper?
Answer: so people learn to drive less with better mpg cars.
Either you're making very profound statements that I cannot fathom or you did not make it to fifth grade math. |
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| mindmachine |
I think you guys who are worried about 20 cents a gallon should consider buying a Honda Civic Hybrid and sell your MDX , invest the money you get back and with the increased income from your investment the gas will almost be free.
$ 20000 invested at 6% interest = $1200 per year for free gas.
$1200/ $3 gal = 400 gal
at 50 MPG x 400 gal = 20000 miles
I bought a $48,000 car and I am going to get premium like Acura recommends and enjoy the performance and the 300 horsies when I want them running smoothly for me.
I may be wrong but everything I ever heard or read said that 10% ethanol actually reduces your performance and MPG. |
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| theseans |
I actually let a 5th grader read this. He blacked out. Anyone know CPR?
quote:
Originally posted by MikeDx
Never really thought of it (have MDX for year+)...
I have to say I agree with all of you (87 and 93), thus every single comment (or most) is correct, even the one about “conspiracy”…(only thought of it now):
Even if you only know 5th grade math, here’s proportion:
If 87x is $3, then 93x is what $? (3*93)/87 = $3.2
Thus mpg is the same!!!
So why not all gas 93 AND cheaper?
Answer: so people learn to drive less with better mpg cars.
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| theseans |
Look, I get where "Squish" is coming from with the price of gas, etc., but it's $200 bucks a year to have more throttle response. It's worth it for that alone.
I guess I just always assumed that everyone on these forums were real hot-rod/car-guys, and wanted to feel that extra torque in the pedal from higher octane. I've been proven wrong by many.
quote:
Originally posted by mindmachine
I think you guys who are worried about 20 cents a gallon should consider buying a Honda Civic Hybrid and sell your MDX , invest the money you get back and with the increased income from your investment the gas will almost be free.
$ 20000 invested at 6% interest = $1200 per year for free gas.
$1200/ $3 gal = 400 gal
at 50 MPG x 400 gal = 20000 miles
I bought a $48,000 car and I am going to get premium like Acura recommends and enjoy the performance and the 300 horsies when I want them running smoothly for me.
I may be wrong but everything I ever heard or read said that 10% ethanol actually reduces your performance and MPG.
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| cjdoors |
No offence to any hot-rod/car-guys (really?) - this is my wife's car - If I could make it run with a rabbit and a carrot when she drives it all week then fire up the engine and pop in a tank of premium for those trips when I drive it and actually use the power, it would be the perfect car.
I do like the suggestion that people drive hybrids, heck - go electrc, even solar. I need those people to keep the demand, and thus cost, of gas down so I can drive my gas hog :)
Needless to say - no written response yet fom my dealer. The bad news - with 112 miles on it, my 3 day old MDX is in the shop, blowing the fuse for the antilock/VSA/AWD system and I haven't even had to make the big decision at the pump yet! |
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| dejavudu94 |
The bottom line is, use whatever you want to use. There are some people on this forum that will argue with you to the death that using one type of octane is the same or better than the other and there is nothing you can say or do to change their minds. If you want to do it, go ahead. If you want to get the maximum benefit from your stock car, use what the dealer recommends. If Acura could get a better horsepower/torque rating and better gas mileage on regular gas, don't you think they would have published these better ratings and recommend we use regular? Remember, this is an advanced 6 cylinder engine that pumps out 300hp. Do people honestly think that Acura advises us to use premium because they just want us to pay more gas? The fact is, your engine was designed to work on a specific type of gas and is tested by certified engineers over and over again to get the maximum benefits out of your engine. You paid $45k for a car, don't you want to get the maximum benefit out of it?
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 you should be ready to switch back to premium at the first sign of knock or other drivability woes. Don't believe me, I don't care. Good luck with your car and continue to do whatever you want to do. Let us know if your engine starts to knock or ping after a while. |
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