Gas Mileage difference

[user 64117]

Started noticing a huge diffence in my gas mileage. I was using 87 octane to save some cake after purchasing the ST. I decided one week (3 weeks back) to stop at a Mobile station and use 89 octane. I usually go to my local Gas Station which is not a named brand to fill up. What i noticed was that the Trac was getting 50 miles better per tank. I assure you that I didn't change my driving habits. At first I thought it was some extra driving on the highway one week, but for the 3rd week in a row, i have benefitted 50 extra miles.



I thought maybe i might have a tune setup for the 89 octane. Does that make sense?



PS: i have not done anything to the Trac, not even adding cleaner to the fuel injectors/gas tank.



Any ideas, Im not complaining by any means, just curious

 

[Keith Lewis]

bad gas will decrease your MPG...

 

[Johnny O]

Within a small window of self-adjustment, 89 octane will let the computer advance your timing a little bit which may give better gas mileage.

A few years ago my dad had a BMW that required premium gas. When gas went over $2 a gallon, he started running 87 but because the computer dialed the timing back the decrease in gas mileage was enough that it actually cost less to run it on 91.

Also different parts of the country get different blends of gas at different times of the year. Where I live we get the crappy oxygenated fuel in the summer. I used to have a 3.0 Ranger that wouldn't run at all and ping like crazy on the summer gas and I had to run at least 89 then. My old 4.0 Ranger and 4.0 Trac aren't quite as fussy about gas but run better on 89 in the summer.

 

[EddieS'04]

I dont buy gas at cut rate stations. Top tier only. Shell, chevron, texaco, mobil, etc.

I personaly and freinds have had pluged filters and sludge from cut rates.

 

[Richard L]

The only way to know for sure is to accurately check your MPG my using accurate miles driven to gallons purchased. Using your gas gauge and tankfulls of gas to measure MPG is like using an hour glass to time a lightening flash.



...Rich

 

[Gavin Allan]

That cut-rate gas was probably 15-20% ethanol, but the Mobil gas is pure, or is only 10%.



You'll get better mileage out of regular Mobil than the cut-rate stuff most of the time.



Gas that meets the TopTier rating is usually the best.

 

[user 64117]

Rich,

your absolutely right on how to measure, and i have taken that method from a previous post when it was mentioned to someone else. I will generally let my tank get down to a 1/8 remaining and then fill up. I have been within 1/2 gallon of each fill up.



what is the size of the Trac's fuel Tank?

 

[Todd Z]

Several people have noticed the same thing.... I remember some posts about that....

You may figure it out that the cost difference is negated by the MPG increase...



Todd Z

 

[Jake Levin]

They just ended winter gas in the NE, I'm already seeing my gas mileage improve. I also saw a jump going from 87 to 93 octane last year.

 

[Richard L]

Gavin is probably correct regarding the amount of ethynol mixed in with the gas, but it cannot legally exceed 10% or 11% because it will damage the fuel system on vehicles designed to run on gas.



Ethynol easy an inexpensive way to raise the octane of gasoline without using the more expensive additives, but gives about 20% less fuel mileage. So if you gas is 10% ethynol, you are getting about 2% less mileage than you would get on pure gasoline.



Most regular gasoline contains higher amounts of ethynol while the higher octane gas has less ethynol and more of the expensive additives. Depending upon the price of gas in our area and the mileage improvement, it may or may not be worth the extra expense.



Even if your engine was tuned for 89 octane, if it runs on 87 octane without pinging, it's prpbably not going to get that much more mileage to warrant the extra cost of switching to the higher octane, but sometimes things work out better.



...Rich

 

[Rodger Tellefson]

I was talking to one of the next door neighbors to my daughter, and he was telling me about driving from Texas to Calif. where he noticed that as soon as he put California gas in his mpg went down - Hummmmm; darn additives.



It's just logical to me that if you are getting better gas milage, you pollute less - Right?



While I am on the subject, roll / rant, I was watching Glenn Beck on HNN where he stated a fact (from his reseach) that was backed up by his panel that 'Pullution in Big Cities has gone Down' in the past 20 yrs. That makes all the whoopla (i.e. Al Gore, etc.) about global warming Political.