Premium fuel vs Regular?

[Forzfed]

I know many people in the past say that high octane fuel is a waste of money especially on an everyday vehicle.  My Colorado use to be crazy consistent in the milage department.  I would always get 32mpg at 60mph.  But lately the best I could muster was 28mpg.  I run nothing but synthetic fluids.  I did a combustion cleaning, injector and MAF cleaning.  I installed new O2 sensors as well.  And still I got the same milage!  I figured I would try some higher octane before I did a trip to the States.  Well I got the best milage ever with the truck, 34 mpg!!!  On 87 running around town I get 150 km out of a 1/4 tank.  If I mix some 91 in there I'm up to 200 Km for a 1/4 tank.  I think this has to do with the fact every low grade gas has to have 10% ethanol because that was around the time I noticed the milage drop.

I've mentioned this to numerous people and some have tried the higher octane and notice an increase in milage as well.  I spoke with some service guys that come to my work and they mention they only use high octane and notice a big improvement.  My one buddy that has a crazy fast 2.2 liter dodge bought his wife a new Dart.  The high octane makes a huge difference in it, cutting 0.5 seconds of the 1/4 mile and giving him almost 8 mpg more on the highway.

What do you guys think?

[Charlief1]

With the control systems on the vehicles these days, the higher octane will allow for more timing so you can get better mileage. When ferd came out with the 5.4 they have knocked frequently. With higher octane the mileage goes up and the knock goes away.

[Forzfed]

I agree with you Charlie!  Especially since lots of the new motors have 10:1 compression or even higher.  But like I said, the truck use to get better milage than lost it.  So now I mix in some 91 that contains no ethanol and my milage has gone up.

[Charlief1]

How many miles on it now?

[Just a Six?]

Just had a talk with my Emissions Mechanic about a 2000 Windstar used for the company & he claims with the Reg Gas & it's 15% Ethanol added it is now technically a "Flex Fuel" which was causing some 02 issues where it would just die at a red light so we stepped up to mid grade fuel of 5% & problem has been solved for 2 months now. I would have never thought it mattered that much but in that city vehicle Ray has way less issues! 

[Forzfed]

How many miles on it now?

It has 117 000 km or 72 540 miles.

[Charlief1]

It has 117 000 km or 72 540 miles.

Change the plugs. The stock plugs are most likely worn and need some help.

[Forzfed]

And with the price difference between the two fuels I still save money because my milage is better.

[Just a Six?]

And with the price difference between the two fuels I still save money because my milage is better.

Exactly! 

[Forzfed]

It has 117 000 km or 72 540 miles.

Change the plugs. The stock plugs are most likely worn and need some help.

Changed the plugs two years ago and I change the fuel filter every 2-3 years.  Also put in a new MAP sensor.  I have a K&N filter, clean it every summer and take the carb cleaner to the throttle body when I do that.

[motorhead]

Shell and Ultramar offer 0% ethanol in their 91 octane fuels, that will translate into about 4% increase in mileage.  Further to this, because most engines have aggressive timing tables at low-load/cruise rpm levels if the fuel is crap and causes the engine to knock, the ECM will continuously pull timing and reduce the overall efficiency of the engine/combustion cycle.

[gordyzx9r]

Shell and Ultramar offer 0% ethanol in their 91 octane fuels, that will translate into about 4% increase in mileage.  Further to this, because most engines have aggressive timing tables at low-load/cruise rpm levels if the fuel is crap and causes the engine to knock, the ECM will continuously pull timing and reduce the overall efficiency of the engine/combustion cycle.

I wish I could find 91 or higher octane ethanol free here.  All I can find is 89.

In my GMC 2500 I was using just regular 87 octane but I noticed under heavy loads it would bog down and the mileage wasn't great (not that I expected it to be).  When I started using 91 or higher, it maintained power under load and I think I went from 12 MPG to 14 MPG. 

[Forzfed]

Shell and Ultramar offer 0% ethanol in their 91 octane fuels, that will translate into about 4% increase in mileage.  Further to this, because most engines have aggressive timing tables at low-load/cruise rpm levels if the fuel is crap and causes the engine to knock, the ECM will continuously pull timing and reduce the overall efficiency of the engine/combustion cycle.

Yup!  And that is what I mix it with.

[Forzfed]

Hey Mike!  Riddle me this, how does nitrogen improve power in Shell gasoline?  I learned in school that nitrogen was bad, causes 1. thermal NOx, 2. fuel NOx, and 3. Prompt NOx.  Hey?  Explain that?

[Steve Wood]

http://www.scientificamerican.com/article/earth-talk-nitrogen-enriched-gas/