Regular Versus Premium Gas

Discussion of Infiniti's amazing (and underrated) sport-luxury crossovers, the EX35 and EX37. For 2014, the EX series will be renamed QX50, in line with Ininfiit's new naming conventions.
wxman
Posts: 69
Joined: Sun Feb 28, 2010 12:34 pm

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Just reviving an old topic...owners manual says use premium but dealer said regular was just fine. I've been using regular since day one and have noticed no issues or problems whatsoever....Also read here that you should run premium through once in a while, but others say pick one or the other since using both interchangeably could screw up the timing. What say you?


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txgcoupe
Posts: 535
Joined: Tue Jan 09, 2007 7:53 am
Car: 2007 G35 Coupe/ 2010 EX35
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The EX and the G35 both get 89 octane. Never a problem.

John


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JCL622
Posts: 301
Joined: Mon Sep 14, 2009 7:02 pm
Car: EX35

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it should be fine. ~ Infiniti takes into account of that possibility, and sets the ratio/mixture in our engine to be able to compensate for a slightly lower grade aka Regular fuel.

If you were to run like lower grade fuel, i would expect some knocking but i'm willing to bet not much. ~ is gas that expensive in your area that it warrants the use of anything below regular?

i've always used 93 tho

akaScott
Posts: 18
Joined: Sat Mar 13, 2010 7:11 pm

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I find that using premium gas gives me better gas mileage (1/2 to 1 mpg) and makes my engine seem a little more responsive. I started using regular, and over time have moved up to 93 octane.

sg77
Posts: 164
Joined: Thu Sep 18, 2008 9:16 pm
Car: 2008 Infiniti EX35
Location: Santa Barbara, CA

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wxman wrote:Just reviving an old topic...owners manual says use premium but dealer said regular was just fine.
The owner's manual (for 2008 at least) actually says this (page 9-3):

"INFINITI recommends the use of unleaded premium gasoline with an octane rating of at least 91 AKI (Anti-Knock Index) number (Research octane number 96).If unleaded premium gasoline is not available, you may use unleaded regular gasoline with an octane rating of at least 87 AKI number (Research octane number 91), but you may notice a decrease in performance."

wxman
Posts: 69
Joined: Sun Feb 28, 2010 12:34 pm

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sg77 wrote:The owner's manual (for 2008 at least) actually says this (page 9-3):

"INFINITI recommends the use of unleaded premium gasoline with an octane rating of at least 91 AKI (Anti-Knock Index) number (Research octane number 96).If unleaded premium gasoline is not available, you may use unleaded regular gasoline with an octane rating of at least 87 AKI number (Research octane number 91), but you may notice a decrease in performance."
It's the same with the 2010 owners manual. But the dealer definitely said regular was fine...didn't even make an issue, he said "it uses regular." I was surprised to see what the manual said. Most of the info I've seen supports the dealer....you can use regular in almost any car except a turbo. If there is a decrease in performance I haven't noticed. There is a rather steep difference in price between regular and premium, and so the only thing I really want to know is am I doing any long term damage. if not, I'll stick with regular. And, yes, I can "afford" premium but I don't think using premium gas is a status symbol, just a waste of money if not needed.

sg77
Posts: 164
Joined: Thu Sep 18, 2008 9:16 pm
Car: 2008 Infiniti EX35
Location: Santa Barbara, CA

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wxman wrote:It's the same with the 2010 owners manual. But the dealer definitely said regular was fine...didn't even make an issue, he said "it uses regular." I was surprised to see what the manual said. Most of the info I've seen supports the dealer....you can use regular in almost any car except a turbo. If there is a decrease in performance I haven't noticed. There is a rather steep difference in price between regular and premium, and so the only thing I really want to know is am I doing any long term damage. if not, I'll stick with regular. And, yes, I can "afford" premium but I don't think using premium gas is a status symbol, just a waste of money if not needed.
I meant that I think the owner's manual agrees with what your dealer said... using regular is ok and shouldn't cause damage. And the reason it shouldn't cause damage is that the engine timing will be adjusted to prevent knocking, at the expense of a little performance (or maybe gas mileage).

Here's an article that discusses it (not specific to the EX or Infiniti, but the general idea): http://www.caranddriver.com/fe...ature
Modified by sg77 at 3:49 AM 3/28/2010

simlam
Posts: 7
Joined: Tue Feb 09, 2010 10:58 am
Car: Ex35

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I normally use Octane 91, but last week, decided to try Octane 94 and the performance difference is quite noticeble. The car responds faster, and acceleration is better too.



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