I will be taking delivery on a 2008 EX today. I noticed in the manual that the fuel requirement was 91 octane. Is premium really necessary? I often wonder when you go to a multi grade pump with only one hose how much premium you really get.

Thanks

Ronnie

Not to be a smart a$$ but if I had a nickel for every time this question is asked on this site I would have more money than Warren Buffet.

91 is recommended. To use lower grade fuel you risk triggering the knock sensors which does produce an engine ping. You can use lower grade if you want but why spend $45M for a vehicle only to periodically spend $150-$200 (uneccesary expense) having those parts of the engine cleaned due to build-up.

It is recommended for a reason. BUT, ultimately you can put in it what ever you like. Just remember, you didn't buy a ford focus and their is a cost associated with driving and owning a luxury car.

I hope you enjoy it. I am stopping in tomorrow to have a peak at an EX up close.

RonnieMartin wrote:I will be taking delivery on a 2008 EX today. I noticed in the manual that the fuel requirement was 91 octane. Is premium really necessary? I often wonder when you go to a multi grade pump with only one hose how much premium you really get.

Thanks

Ronnie

Recommended fuel - Premium (recommended)

You don't HAVE to use premium, but you will get better MPG and performance running premium.

My weekend fun car, a Classic Red Mazda Miata, which I've owned for over 6 years, also requires 91 octane (recommended). I have run some test runs using both regular gas and mid-grade and I definitely get better gas mileage with the premium. About 1-2 mph better mileage. I average at least 27.5mpg with the premium and it got as low as 25.8 with regular. I tried to maintain equal driving conditions during these tests. My math results were:

12000 miles / 27.5mpg = 436.36 gallons x $3.35 = $1461.8012000 miles / 26.5mpg = 452.83 gallons x $3.05 = $1381.1312000 miles / 25.8mpg = 465.12 gallons x $3.05 = $1418.62

As you can see, if I average as little as 1mpg difference, the total fuel cost per year only goes down by about $80. That's less than $7 per month.

Assuming the same difference for the EX (with its expected lower MPG):

12000 miles / 22mpg = 545.45 gallons x $3.35 = $1827.2612000 miles / 21mpg = 571.43 gallons x $3.05 = $1742.86

Again, only about $80 difference.

Using regular gas when the car calls for Premium is false economy, particularly when you consider the possibility of pinging or other driveability problems.

Mark

Here's a direct quote for the EX35 manual:

"FUEL RECOMMENDATIONVQ35HR engineINFINITI recommends the use of unleaded premiumgasoline with an octane rating of at least91 AKI (Anti-Knock Index) number (Researchoctane number 96).If unleaded premium gasoline is not available,you may use unleaded regular gasoline with anoctane rating of at least 87 AKI number (Researchoctane number 91), but you may notice adecrease in performance.CAUTIONc Using a fuel other than that specified couldadversely affect the emission control system,and may also affect warranty coverage.c Under no circumstances should a leadedgasoline be used, because this will damagethe three-way catalyst.c Do not use E-85 fuel in your vehicle. Yourvehicle is not designed to run on E-85 fuel.Using E-85 fuel can damage the fuel systemcomponents and is not covered by theINFINITI vehicle limited warranty.Gasoline specificationsINFINITI recommends using gasoline that meetsthe World-Wide Fuel Charter (WWFC) specificationswhere it is available. Many of the automobilemanufacturers developed this specificationto improve emission system and vehicle performance.Ask your service station manager if thegasoline meets the World-Wide Fuel Charter(WWFC) specifications.Reformulated gasolineSome fuel suppliers are now producing reformulatedgasolines. These gasolines are speciallydesigned to reduce vehicle emissions.INFINITI supports efforts towards cleaner airand suggests that you use reformulated gasolinewhen available.Gasoline containing oxygenatesSome fuel suppliers sell gasoline containingoxygenates such as ethanol, MTBE and methanolwith or without advertising their presence.INFINITI does not recommend the use of fuels ofwhich the oxygenate content and the fuel compatibilityfor your INFINITI cannot be readilydetermined. If in doubt, ask your service stationmanager.If you use oxygenate-blend gasoline, pleasetake the following precautions as the usage ofsuch fuels may cause vehicle performance problemsand/or fuel system damage.c The fuel should be unleaded and have an octanerating no lower than that recommendedfor unleaded gasoline.c If an oxygenate-blend, excepting a methanolblend, is used, it should contain no more than10% oxygenate. (MTBE may, however, beadded up to 15%.)c If a methanol blend is used, it should containno more than 5% methanol (methyl alcohol,wood alcohol). It should also contain a suitableamount of appropriate cosolvents andcorrosion inhibitors. If not properly formulatedwith appropriate cosolvents and corrosioninhibitors, such methanol blends maycause fuel system damage and/or vehicleperformance problems. At this time, sufficientdata is not available to ensure that allmethanol blends are suitable for use inINFINITI vehicles.If any undesirable driveability problems such asengine stalling or hard hot starting are experiencedafter using oxygenate-blend fuels, immediatelychange to a non-oxygenate fuel or a fuelwith a low blend of MTBE.Take care not to spill gasoline during refueling.Gasoline containing oxygenates can cause paintdamage.Technical and consumer information 9-3"

Hope this helps