Fuel octane

E

elder3

Member
Location
arlington texas
Hi.. I'm new here... i just recently purchased a 2009 FX-35 for my wife. 1 question... i would appreciate any experiences members have had with mixing regular or mid-grade with premium grade fuel. with the price of gas these days... I have to ask...:smile (2):
 
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Buy premium only. If you concerned about 10-20 cents difference, maybe you shouldn't have purchased this car. No offense. Can you use regular gas?-YES. But you will waste lots of it and overall will drop MPG and in long run will spend same money on regular gas as if used premium gas. Performance and most luxury cars require premium gas not for wasting your money, but due to engine requiring premium fuel to operate effeciently and on it's best.
 
Locally, i get the same crappy mpg (~12mpg) with both premium and regular. Controlling your foot and being light on the pedal makes the biggest difference here.

Highway, theres a noticeable difference in miles per tank when using premium and regular. Of course, granted you are using cruise control, ~70mph and not always speeding up/slowing down.

The optimal cruising speed it seems is around 65mph.

Good luck! Agreed with you on the increasing price costs these days. Must keep an eye out on our finances and there is nothing wrong with that :smile (2):
 
I don't think I've ever filled up past 20 gallons, so I'm guessing 22-24.

Edit: 23.8 per a post by gto elsewhere.
 
Premium only - gives you the best mpgs over all, making it less expensive than the mid grade octane if you count how many miles each tank will give you.
 
I was using mid grade for a while, switched to premium because the sam's club is cheaper and I have definitely noticed a difference in the mpg. I had the G37s coupe before and only used premium in that and figured this is an SUV and doesn't need have the high performance engine, but exactly that, for the couple dollars difference in the long run it is better to use premium.
 
I use premium only. Gas prices are sky high here in L.A. The difference in savings in terms of percentage from mid-grade to premium becomes smaller and smaller the higher the prices become.
 
Just curious, by premium do they mean 91 or 93? Ive been putting 93 since I got the car a couple years ago but as I was filling up today, I noticed 91 said "premium" on the pump and 93 said "ultra". Is the fx optimized for 91?
 
OSUFX said:
Just curious, by premium do they mean 91 or 93? Ive been putting 93 since I got the car a couple years ago but as I was filling up today, I noticed 91 said "premium" on the pump and 93 said "ultra". Is the fx optimized for 91?
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This is something I noticed today as well. Filled up at Sunoco and realized that they have a 91 octane option. The norm in NYC is 87, 89, or 93.

Is using 93 just as negligible as using 101 race gas?
 
You can run anything you want, you'll gain power as octane goes up, and from above, it affects the FX mpg. Really little difference between 91 and 93, if it's gonna ping it will do it with either.

Fwiw I had a g35 and I ran mostly 87 in it for over 100k miles. Given, it was a highway commuter (rarely past 2/3 throttle ) bit still ran good as new at 100k+. Perhaps mpg was suffering, I never calculated.
 
Fire0nic3FX said:
I wish we had something better than 93 here in NY.

I hear there is a Shell gas station in Long Island that sells 101 octane.
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Be glad your not in California with the highest octane being 90-91 ethanol blended california EPA mix unless you go to a specialty station and buy 101 octane without ethanol blended fuel for 8.75 a gallon. I do run the 101 in my Norton though :)
 
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pmanliu said:
Locally, i get the same crappy mpg (~12mpg) with both premium and regular. Controlling your foot and being light on the pedal makes the biggest difference here.

Highway, theres a noticeable difference in miles per tank when using premium and regular. Of course, granted you are using cruise control, ~70mph and not always speeding up/slowing down.

The optimal cruising speed it seems is around 65mph.

Good luck! Agreed with you on the increasing price costs these days. Must keep an eye out on our finances and there is nothing wrong with that :smile (2):
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12mpg? You have it floored all the time? I average 17mpg with my Denver City commute and that involves a lot of pedal stomping in traffic. I just did a round trip to Telluride and back (600 miles diagonal across Colorado through the mountains) and averaged 25mpg. Cruise control greatly helps MPG. So far I have only ran mid grade in it. I am going to try some premium (only 91 octane at this altitude) and see how it does.
 
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