Is it my imagination?
- Thread starter chefster
- Start date
I've been told by pretty much everybody that you wanna run the lowest grade you can without detonation, and that unless you have the compression for it, premium isn't doing anything except emptying your wallet.
That aside, i've tried to run 87 in my car and it feels like a pig. I have the timing at 14* which i don't think should be enough to cause detonation with around 9:1 compression ratio.
That aside, i've tried to run 87 in my car and it feels like a pig. I have the timing at 14* which i don't think should be enough to cause detonation with around 9:1 compression ratio.
Really, the only reason you need premium is to avoid detonation. It has no other performance or mileage benefit, and anybody who says that it "cleans out your engine" should climb out of the 1950s. Premium just has greater resistance to compression-ignition (the cause of "knock") than regular-grade does.
If you really think you are getting better mileage on premium, I'd check to see if the regular-grade gas you are buying is 10% ethanol blend. Some gas stations carry this as their regular-grade and you won't see quite as good gas mileage on this blend. I'm not sure, but I don't think you can buy ethanol blended premium, so in that sense, you would actually see better mileage from the premium.
If you really think you are getting better mileage on premium, I'd check to see if the regular-grade gas you are buying is 10% ethanol blend. Some gas stations carry this as their regular-grade and you won't see quite as good gas mileage on this blend. I'm not sure, but I don't think you can buy ethanol blended premium, so in that sense, you would actually see better mileage from the premium.
Mr. Rustypwnz
Advanced Member
do your research before saying this man.. premium actually has alot less energy stored, because of this it is more stable, and that is why we have to run it with boost or higher compression, premium also has fuel mileage adders mixed in along with some other solvents, to help clean the lines and injectors. So yes you really do get better mpg with premium, even with upped timing, boost or compression, ive done it on 3 different cars and I gained anywhere from 2-5mpg better, however on a stock car like my notch it does give it a little bit better mpg like 1-2mpg at the most.
YES it does work!!! if you dont believe me try it..
I can't say I've ever heard this before. What exactly is a "fuel mileage adder"? In all the research I've done (but I'm no expert), my understanding is that all grades of gasoline receive the same amount of stabilizers/solvents, regardless of octane rating.
Seriously, though, what is a "fuel mileage adder", and where can I buy it?
MAC'n89Blckstng
Active Member
My dad was in the boat of anything other than regular is a rip off. Then he started to put premium in his 03 Maxima and said there was a noticeable difference in how it runs and the mileage was much better. And my dad would be the last person I would expect to say that. He's the king of saving as much money as he can. lol
25thmustang
Mustang Master
I've tried this, not once did I get better mileage and have had the best running 89 octane and 18 degrees of timing. In my Audi I saw no difference in running a tank of 91 vs 93. Is it the big oil companies telling you there is a gas mileage additive in the more expensive gas? If it is... well not much more I can say.
I might try it again with my F250, after all any and all mpg saved in that is worth it.
The is not true. The additives used to keep injectors clean is added to all grades of gas depending on brands. Some brands may have more/better additives than no-name stations. They aren't just dedicated to higher octane level fuel. I'd also like to know what this "fuel mileage adder" is.
Only difference between the grades is the ROM + MON/2 value to which it resists detonation.
The lower the octane value, the more potential energy is stored.
Keep in mind the engine is engineered around a specific octane level for a reason. Compression/boost/timing/fuel etc is based off it. We don't modify our engine to run a specific octane level, we run a specific octane level because our engine is modified.
Of course there are also exceptions. A lot of engines don't have knock sensors and sometimes running a low octane level in a worn engine with hot carbon deposits artificially inflates the octane level required for proper operation.
A blanket statement like "higher octane gets you better fuel economy" doesn't always apply to every car. There are just WAY too many variables.
I run 87 octane in my '03 GT. I get zero detonation and it runs smooth. I've tried hogher octanes, and noticed ZERO difference except out of my wallet. I've logged my milegage and have gotten 25-26MPG highway consistenly with 87 or 93. But anytime anyone asks me about my car (at work, gas station, out driving) and they hear i put 87 octane in it, they shake their head like I don't care about the car at all and should put premium. Marketing 101 at it's best...right up there with platnium spark plugs
To add to that, in an unmodified, perfectly running, vehicle....the recommended octane will net you the BEST mileage, period.
People with a perfectly running, unmodified, vehicle that is engineered to run on 87 octane, will typically get worse mileage if you use higher octane, mainly due to the fact that the engines sensors will alter the trims and timing to properly burn the fuel.....causing you to LOSE mileage.
A perfect example is my last DD, a 99 Cougar 2.5, MTX. When I first bought it I played the "more is better game" and ONLY ran it on 93 octane...the few times I filled up with 87 I would get detonation. After deciding to learn about fuels and octane ratings, I kept with 87 octane. After two or three tanks, the detonation went away...and I got BETTER mileage, doing the same exact driving. I went from a consistent 295-300 miles per tank to 305-320.
There are no "mileage adders" in ANY fuel. Different stations (Shell, Mobile, Hess, ect) use different additives, cleaners, ect. But typically speaking, unless you are getting bad gas....there will be no noticeable difference in mileage between stations.
People with a perfectly running, unmodified, vehicle that is engineered to run on 87 octane, will typically get worse mileage if you use higher octane, mainly due to the fact that the engines sensors will alter the trims and timing to properly burn the fuel.....causing you to LOSE mileage.
A perfect example is my last DD, a 99 Cougar 2.5, MTX. When I first bought it I played the "more is better game" and ONLY ran it on 93 octane...the few times I filled up with 87 I would get detonation. After deciding to learn about fuels and octane ratings, I kept with 87 octane. After two or three tanks, the detonation went away...and I got BETTER mileage, doing the same exact driving. I went from a consistent 295-300 miles per tank to 305-320.
There are no "mileage adders" in ANY fuel. Different stations (Shell, Mobile, Hess, ect) use different additives, cleaners, ect. But typically speaking, unless you are getting bad gas....there will be no noticeable difference in mileage between stations.
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