I was always told that premium gas is only better if your car is tuned for it. My brother was telling me he puts Shell premium in his stock Mazda 6 and gets noticeably better gas mileage. So I try it in my truck, non s/c hd f150, and I got 1-2 mpg more than I usually do. Not a bad gain when your at 14mpg. The only thing that I can think of is maybe it doesn't have ethanol in it? So what do you guys use?
What gas do you guys use?
- Thread starter 99GTvert
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Thats not how gasoline octane ratings work.
93. Truck is tuned for it.
i use premium because im tuned for it, but even on stock, you do get better mileage and the gas burns better in the engine
I use 89 in my DD and 93 in my 84 c10
Absolutely incorrect.
Premium all the time. Once the cars learns the octane, I believe it has perimeters that adjust timing and slightly lean the a/f in a linear trend from the base 85 or 87 tune. Similar to knock sensors or maf sensors pulling timing and fattening a/f when a problem is detected, I believe premium fuel, once learned (20~minutes?) signals the computer to do the opposite to a slight extent based on manufacturer preset fuel tables.
My 98 Yukon gets roughly 15mpg on premium (91 oct) but only 13.5~ on 85. It's now nat gas converted so I've stopped keeping track.
My fx35 feels sportier on premium and lack luster on 87. My friends Rsx Acura got 3mpg better with premium over 85. I believe large motors receive less of an effect than small motors as my Yukon had the exact same feel on lower fuel but my friends Acura felt much livelier around 6-7500rpms.
My 98 Yukon gets roughly 15mpg on premium (91 oct) but only 13.5~ on 85. It's now nat gas converted so I've stopped keeping track.
My fx35 feels sportier on premium and lack luster on 87. My friends Rsx Acura got 3mpg better with premium over 85. I believe large motors receive less of an effect than small motors as my Yukon had the exact same feel on lower fuel but my friends Acura felt much livelier around 6-7500rpms.
Care to explain? I've had very different results than yours. Could air density/weather play a factor? I'm 4500ft high in a cool mountain state. Thanks in advance for any info.
Sure.
Octane ratings are simply a scale measuring the ability of fuel to resist detonation. Higher octane = harder for detonation to occur as it's more robust.
If you run say 93 octane in a car designed for 87 octane, you're just throwing your money away. The only reason to ever increase your octane is if detonation(pinging) occurs.
Your car cannot magically decide "Hey, Im getting higher octane fuel, better increase my compression ratio and add timing to my motor." Doesn't work like that.
Also, switching to 93 octane vs. 87 octane will not "clean" a motor better nor will it produce better fuel economy assuming 87 octane is the fuel intended for the application.
Also keep in mind that there typically is no such thing as 91 octane fuel. "Midgrade(typically labeled 91 octane)" is generally a mixture of their "premium" fuel and their "regular" grade fuel.
The terms "Regular, Plus, and Premium" are marketing ploys. The customer says well if thats premium and this is regular then it must be better! Hogwash designed to make you spend an extra 20-30 cents more per gallon.
Think about it, if 93 was better than 87 in all applications, then why wouldnt everyone buy 93 or better yet 100 octane?
Essentially the answer to what fuel you should run is simple. Refer to your owner's manual or your tuner.
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I can't comment on that specifically but I would say No if i had to guess.
Have you ever seen an owner's manual state "87 octane if in Mexico, 93 octane if in Denver?"
This is absolutely true of older models. I am not so sure it it true with the newer stuff. My 2012 focus manual says it is designed to run on the lower octane fuel but it also says that I will see some performance improvements if I should choose to run premium fuel.
76 Union.
87 octane in Explorer and Toyota
91 octane in Cobra (it's the best available in California)
87 octane in Explorer and Toyota
91 octane in Cobra (it's the best available in California)
91 (highest available in Nevada) in the GT
87 in the 03 Dodge Ram.
If I'm feeling baller-status, my Ram will get the 91 as well. Does it make a difference? Meh. 1-2mpg according to my mpg reader-thing on the overhead display. Kind of makes a difference when you're talking about a 25 gallon tank.
Edit: Using a knock sensor on a buddies SRT4 skittle, we determined the "best" gas to be from the Rebel stations in Vegas. He is very highly modded and running upwards of 15+psi.
87 in the 03 Dodge Ram.
If I'm feeling baller-status, my Ram will get the 91 as well. Does it make a difference? Meh. 1-2mpg according to my mpg reader-thing on the overhead display. Kind of makes a difference when you're talking about a 25 gallon tank.
Edit: Using a knock sensor on a buddies SRT4 skittle, we determined the "best" gas to be from the Rebel stations in Vegas. He is very highly modded and running upwards of 15+psi.
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What about slightly modded cars with CAI and full exhaust system. I feel like if the car was stock and using 87 octane, everything would work together. But now that there is more airflow involved, wouldn't the computer had to do big adjustments?
No. Unless you have had the car tuned to utilize more airflow, it would be a waste.
Remember that most cars from the factory are tuned pretty rich. It would take much more than an intake to make them run lean and detonate.
I ran 87 in my F150 5.4 towing the Cobra to Bristol a few years back. Got 12 MPG. Once in Bristol and all my runngin completed and we were ready to head back home I filled up with 93 premium. I got over 12.5 almost 13 mpg on the exact same route. It wasn't much difference but I could tell some difference and the gas mileage showed it.
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