Topic: Regular Unleaded in a Premium Vehicle
in Forum: Off Topic
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C3VR Founder
Eagleville, PA - USA
Joined: 11/1/2001
Posts: 18566
Vette(s): Used to own a 1979 Corvette now owned by JB79
"My friend" bought an Acura MDX a couple of months ago. Since then, "my friend" has been putting regular (87 octane) unleaded fuel in it. Today when "he" was filling up "his" tank, "he" noticed the Premium Fuel Only label on the fuel door. "He" looked in the manual and it said it needs 91 octane or better. The manual said use of a lower octane will cause occasional mechanical pinging and descrease engine performance.
What are ALL the issues with using lower octane?
Can it be damaging to the engine, or is it just a matter or performance?
Is MPG affected?
Is it worth the extra 40 cents per gallon for the 93 octane stuff?
"My friend" thanks you for your help!
What are ALL the issues with using lower octane?
Can it be damaging to the engine, or is it just a matter or performance?
Is MPG affected?
Is it worth the extra 40 cents per gallon for the 93 octane stuff?
"My friend" thanks you for your help!
-Adam Wartell
NCM Lifetime Member #1222
Founder: C3 Vette Registry
C4 Vette Registry, C6 Vette Registry
My first Vette, now owned by JB79:

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Summerville, SC - USA
Joined: 8/31/2005
Posts: 660
Vette(s): My 1974 Vette sold last August 2014. I am still willing to show up to events and local gatherings if anything happening No new vette yet.
well, i accidentally put regular in my vette for a bit before noticeing it needed premium. afterwards, i got better acceleration and better mileage to the tank. it didnt run so rough either. so yeah the grade does make a difference in my opinion.
Jeremy
Your Acura probably has a knock sensor. So when the regular fuel starts to ping/knock, the sensor will retard the timing until it stops. This means you are always running retarted timing, and as such will get less power, and MAYBE less fuel mileage.
Try a tank or two of 91 and watch the mileage. If it improves enough to make up for the difference in cost, you are ahead with the 91. It will run better.
If the fuel savings are not there, and you don't mind the way it runs, it won't hurt anything.

C3VR Founder
Eagleville, PA - USA
Joined: 11/1/2001
Posts: 18566
Vette(s): Used to own a 1979 Corvette now owned by JB79
[QUOTE=kstyer]Your Acura probably has a knock sensor....[/QUOTE]
Who said it was mine? 

Seriously, though....thanks for the advice!
-Adam Wartell
NCM Lifetime Member #1222
Founder: C3 Vette Registry
C4 Vette Registry, C6 Vette Registry
My first Vette, now owned by JB79:


Greensburg, IN - USA
Joined: 9/24/2003
Posts: 5189
Vette(s): Previous: 1984 Coupe, 1988 Maroon Coupe, 1989 Coupe, 2001 Roadster Present: 1967 Stingray Roadster, 1976 Stingray Coupe, 1989 Roadster..
[QUOTE=kstyer] Your Acura probably has a knock sensor. So when the regular fuel starts to ping/knock, the sensor will retard the timing until it stops. This means you are always running retarted timing , and as such will get less power, and MAYBE less fuel mileage.
Wow, Ken only you could get away with tellin he's runnin his car retarded...
Try a tank or two of 91 and watch the mileage. If it improves enough to make up for the difference in cost, you are ahead with the 91. It will run better.
If the fuel savings are not there, and you don't mind the way it runs, it won't hurt anything.
[/QUOTE]
Wow, Ken only you could get away with tellin he's runnin his car retarded...


I just sold my 2003 TL/S with 90,000 miles on it. I always used the 87 octane and was never disappointed with the performance. Highway milage was over 30 MPG and I saved about $1,200. at the pump. The way I look at it is while the Acura might have been retarded I wasn't.
in Forum: Off Topic
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