Acura MDX SUV Forums banner

1 - 20 of 31 Posts

·
Registered
Joined
·
3 Posts
Discussion Starter #1
I know there are endless online discussions about this topic. From what I'm reading, 87 perfectly fine, given all the sensors and and computer aided timing, but to get maximum performance and efficiency 91 is recommended? Anybody disagree?

What I also don't understand is the Honda Pilot has identical compression ratios, and only requires 87. Are there other elements of the engine that are benefiting from 91? Thanks!
 

·
Registered
Joined
·
3,116 Posts
There should be a sticker on the inside of the fuel door. It states on my 18 RLX and 19 MDX "87 Minimal and 91 recommended". I couldn't find anywhere in my 19 MDX or 18 RLX owner's manual saying 87 octane minimal (only 91 octane). I would go with the fuel octane rating you want as long as you don't go below 87 Octane. I get my fuel from Sam's or Costco at home and when I travel and stick with 91 Octane (91 Octane at Sam's/Costco is almost same price as 87 Octane at a corner gas station).
 

·
Registered
Joined
·
30 Posts
I know there are endless online discussions about this topic. From what I'm reading, 87 perfectly fine, given all the sensors and and computer aided timing, but to get maximum performance and efficiency 91 is recommended? Anybody disagree?

What I also don't understand is the Honda Pilot has identical compression ratios, and only requires 87. Are there other elements of the engine that are benefiting from 91? Thanks!
Pilot = 280 HP, MDX = 295 HP, they are tuned differently, I would go with what the manufacturer recommends which is 91 (premium), but it is your vehicle so you can do what you want.
 

·
Registered
Joined
·
3,116 Posts
You only get the 290 hp at 6200 rpms at sea level. Probably a much smaller hp and mpg difference between the Pilot and MDX (if any) in normal city or hwy driving. Just on paper, the Pilot and MDX engine seem 99.9% identical. I would think it would be a bonus feature to have the +22 MDX normally run on regular and have a power boost with +91 Octane.

Even my RLX sport hybrid with the 310hp/273tq 3.5L+hybrid powertrain can take regular.
 
  • Like
Reactions: rstotl01

·
Registered
Joined
·
341 Posts
I used to only run 91 on my MDX, then switched to 87 last September. No noticeable difference in fuel economy or performance so I have no reason to switch back.
 
  • Like
Reactions: bdh075 and rstotl01

·
Registered
Joined
·
30 Posts
So you are saying if a person runs regular they get 280 but they run premium they get 295 hp? Based on your logic, the Pilot only achieves 280 hp at 6200. I am quoting HP numbers directly from Honda and Acura. I do not believe you gain a 15 hp advantage by burning premium, it is because the motors are tuned differently which is why it is recommended to run 91 octane or higher. Will the MDX run okay on regular? Yes but you are depriving yourself of maximum performance. This question has been beaten around since the launch of the MDX and if you can afford an MDX you should not have a problem buying premium as the manufacturer recommends. But some people want to cheap out, those folks should have bought a Honda.
 

·
Registered
Joined
·
3,116 Posts
So you are saying if a person runs regular they get 280 but they run premium they get 295 hp? Based on your logic, the Pilot only achieves 280 hp at 6200. I am quoting HP numbers directly from Honda and Acura. I do not believe you gain a 15 hp advantage by burning premium, it is because the motors are tuned differently which is why it is recommended to run 91 octane or higher. Will the MDX run okay on regular? Yes but you are depriving yourself of maximum performance. This question has been beaten around since the launch of the MDX and if you can afford an MDX you should not have a problem buying premium as the manufacturer recommends. But some people want to cheap out, those folks should have bought a Honda.
The +2014 MDX and +22 MDX DI and port injection engines are designed to run on +87 Octane unleaded fuel with up to 15% ethanol. My 06 TSX, 08 RDX, and 11 MDX was +91 Octane required and I always stuck with 91 Octane for every Acura. I think it is great Acura has designed such a flexible engine to fit the needs of the owner.
 
  • Like
Reactions: rstotl01

·
Super Moderator
Joined
·
1,866 Posts
From where I read earlier.... go with what it "REQUIRED" (due to how engine is tuned). Looks like both 3rd and 4th Gen MDXs are required 87+, but recommended 91+. It should be fine to run on 87 (regular) grade. I have always fill with 93 from Costco since I have 3 Costco gas stations within 15 minutes radius (in three direction) and it is either on-par or cheaper compare to regular grade off local gas station (i.e. Exxon, Sunoco, shell, etc).
 

·
Registered
Joined
·
30 Posts
As I said, you can use regular but you get decreased performance, why does everyone try to make this seem so difficult? Use premium for best performance use regular for decreased performance.

From the owners manual:
■ Fuel recommendation
Unleaded premium gasoline, pump octane number 91 or higher
Use of a lower octane gasoline can cause occasional metallic knocking noise in the engine and will result in decreased engine performance.
Use of a gasoline with a pump octane less than 87 can lead to engine damage.
 

·
Registered
Joined
·
341 Posts
This question has been beaten around since the launch of the MDX and if you can afford an MDX you should not have a problem buying premium as the manufacturer recommends. But some people want to cheap out, those folks should have bought a Honda.
Many of us don't use this vehicle for performance. It is not a sports car.
I can afford premium fuel, but I drive average speeds and accelerate at the same rate as everyone else so I will never feel the 10 extra HP this engine makes over the Pilot. Because of this, I have no incentive to spend an extra ~60 cents per gallon on premium fuel. This is not being cheap, this is being smart with money. I'm sorry you feel I don't deserve to own an Acura because of this.
 

·
Registered
Joined
·
13 Posts
But some people want to cheap out, those folks should have bought a Honda.

That presupposes that slightly better performance is the reason somebody wants the Acura. If the main thing somebody purchased an MDX for is the nicer interior and better features they might not really care about spending hundreds more a year for a few percent more horsepower. A lot of drivers almost never floor it in their cars and wouldn’t likely notice. So long as it makes no reliability difference, there isn’t a major reason for a driver who isn’t into maximum performance to buy the fancier gas.
 

·
Registered
Joined
·
16 Posts
Honestly, you are driving an SUV to do daily task. Not sure if premium fuel is needed unless you are driving spirited like a sports car or towing. V6 is a great flexible engine, unlike turbo. I also used premium gas on 1gen Acura RDX since it is turbo and designed to rev up!
 
  • Like
Reactions: rstotl01

·
Registered
Joined
·
1 Posts
Below is from 2022 MDX manual...

116771


I know there are endless online discussions about this topic. From what I'm reading, 87 perfectly fine, given all the sensors and and computer aided timing, but to get maximum performance and efficiency 91 is recommended? Anybody disagree?

What I also don't understand is the Honda Pilot has identical compression ratios, and only requires 87. Are there other elements of the engine that are benefiting from 91? Thanks!
 

·
Registered
Joined
·
3,116 Posts
Below is from 2022 MDX manual...

View attachment 116771
Thanks for the info in manual. Confirms what was said before of being A-OK with using 87 octane or higher for the +22 MDX. The MDX will adjust the timing to reduce or eliminate the knocking. Some parts of NM and west TX only have 86 or 90 octane at the pump is the reason why I only use 90/91 octane (whatever happened to mid-grade).
 

·
Registered
Joined
·
30 Posts
Many of us don't use this vehicle for performance. It is not a sports car.
I can afford premium fuel, but I drive average speeds and accelerate at the same rate as everyone else so I will never feel the 10 extra HP this engine makes over the Pilot. Because of this, I have no incentive to spend an extra ~60 cents per gallon on premium fuel. This is not being cheap, this is being smart with money. I'm sorry you feel I don't deserve to own an Acura because of this.
The difference is 15 HP and Premium in WA is 0.20 per gallon more than regular. In addition to reduced performance you will probably get worse MPG’s which has been my experience. So who is really being smart with their money😜
Oh BTW, you have my permission to run regular in your MDX, it is yours to do with what you want. I will run premium in mine for top performance and better MPG’s! And I never said you don’t deserve to own an Acura, I said those who choose to run regular in an Acura should have bought a Honda🤦‍♂️
 

·
Registered
Joined
·
325 Posts
Acura says IIRC "premium recomended" not "premium required" My other cars are "premium required" and we also use premium in the MDX. usually costs another $0.20-0.30 gallon. and at 26 mpg average in town with the hybrid, not a big deal for us, it's up to you to decide what you want to run.
 

·
Registered
Joined
·
3,116 Posts
Both the 3rd Gen and 4th Gen 3.5L engine is rated at 290hp. Only the RLX 3.5L is rated higher at 310hp for both the hybrid and non-hybrid versions.

I live and drive mostly at 5000-6800 feet. I'm already down on hp for the NA engines by 15%-20%; which, make the engine work harder compared to lower altitude vehicles to maintain the same performance. Factor in posted speed limits of 75-80 mph (set my ACC 5-7 mph above that). I like the feature with the Acura (you can't get with the Honda) of getting a touch more performance with 91 Octane. Plus, you will see regular 85-86 octane gas sold at higher altitudes because of thin air and richer air-fuel ratio (87-88 for mid-grade) Using 87-88 octane in Denver or ABQ is probably like using mid-grade 89 octane near sea level.

I lived in Seattle/Tacoma and Phoenix in my younger days with commute times of 10-20 hrs weekly of sitting in my car inching forward slowly. I can understand one of the reasons for using the 87 octane option for the MDX. My commute is now 2 miles in New Mexico and I usually ride my bike to work.
 

·
Registered
Joined
·
13 Posts
The difference is 15 HP and Premium in WA is 0.20 per gallon more than regular. In addition to reduced performance you will probably get worse MPG’s which has been my experience. So who is really being smart with their money😜
Oh BTW, you have my permission to run regular in your MDX, it is yours to do with what you want. I will run premium in mine for top performance and better MPG’s! And I never said you don’t deserve to own an Acura, I said those who choose to run regular in an Acura should have bought a Honda🤦‍♂️
20 cents more is amazing. In my area it is 60 cents.
 

·
Registered
Joined
·
1,049 Posts
116784
 
  • Like
Reactions: drshaun

·
Registered
Joined
·
997 Posts
20 cents more is amazing. In my area it is 60 cents.
In my area premium is $.74 to $1.00 more than regular (except at Sam's & Costco).
Premium varies from $3.20 to $3.99 depending on location (except Sam's and Costco). I filled up with premium in the S550 this past Saturday at Sam's for $2.51. Typically Sam's premium is cheaper than most places' regular.
 
1 - 20 of 31 Posts
Top