what octane? PU241

[easywind]

I see in a discussion about gas mileage that you said you're using (89) mid grade fuel in a Festiva. Why?
Glad you're home safe, good luck with the new car.

[Pu241]

I use 89 because during testing I found approximately a 3-4 mpg improvement over 87 octane.
More in the Summer less in the Winter
I also found no improvement using 91/93 premium fuel.
And when gas spiked around here to $3.25+ for 89 octane I relented and tried running the 87 and most definitely saw my MPG drop.
Don't take my word for it!
Easy experiment, you should already have a log of your fuel usage and maintenance records, if not start now, if your serious about MPG!
I use a 4x6 spiral bound card notebook, mainly because it fits in the glove compartment.
If not collect the data:
5 tanks of regular 87 calculate MPG per tank
5 tanks of 89
you can also do the premium if you desire.
Maximum cost of experiment over normal fuel costs
50 gal x $0.10 per extra cost for 89 octane = $5
Example:
Increase your MPG from 40 to 42.
Means you get another 20 miles or 1/2 gal of fuel out of the same 10 gallons.
Which you paid an extra $1 for but is now worth $1.50 so you save $0.50.
If you currently get less than 40 MPG then that increase need not be as much to break even or come out ahead.
I also think it runs better but have no data to confirm.
Maybe more importantly is the state of maintenance of your vehicle;
tire pressure, air filter, oil change interval, ignition components.
Then there the number one deter minor of MPG, driving style!
Which is closely related to speed!
I found a longer but lower speed route to work.
MPG in the Fall was in excess of 54 mpg, but my average speed was probably 50 MPH!
Those are the facts as I have them recorded!

[todd00]

ive never used the ethanol 89 octane gas. it basically ruined an 83 sapporo i had, so ive never touched the stuff since then.

[Pu241]

ive never used the ethanol 89 octane gas. it basically ruined an 83 sapporo i had, so ive never touched the stuff since then.

No one said anything about "ethanol 89 gas"!
Just to clarify though in my above post I'm referring to 89 octane gasoline.
Just a note; gasohol will not give better MPG, the 10% ethanol reduces the BTU content of the fuel and thus mileage.
In theory you could raise the compression ration to improve it but it will not give you the same MPG as straight gasoline.
Shortly Todd00 you wont have any choice but to use gasohol! :evil:

STEPPING UP ON SOAP BOX
While were at it remember to smile when you have to buy gasohol or E85
because the government has, through it infinite stupidity, decided it is going to produce 36 billion gallons of ethanol.
Which produces less MPG and is a best a break-even proposition considering the energy costs in producing it.
Also remember to thank the government when your food bill goes up because corn(at least initially) will be used to make ethanol raising prices for corn flakes, stake, hamberger, pork, and chicken.
So we all get to pay ether at the pump or at the grocery story!
STEPPING OFF SOAP BOX

[jglutz]

^^the goverment always wants to protect consumers.....they just do it form the side of the supplier.

[todd00]

the ethanol in 89 octane is all they offer here. they offer a prem regular unleaded and the regular 87. of course im in corn country2.

so i assumed thats what you were referring to.

[easywind]

Interesting and it's worth a couple of tankfulls. I also presume one will not get that type of gas mileage with a lead foot. I never got over 30/31 but my driving style is not conducive to getting good mpg.
I also see our government is trying to keep us safer by levying fines of up to $900 for speeding along certain NE corridors.

[Pu241]

the ethanol in 89 octane is all they offer here. they offer a prem regular unleaded and the regular 87. of course im in corn country2.
so i assumed thats what you were referring to.

Ah, now I understand!

Sorry to hear that!
Seems to me then you need to run a few tanks of each to see where if you can get any advantage from the higher octane fuels. Car fuels systems today will tolerate ethanol. Back in late 70's early 80's they were just realizing all the fuel system couldn't handle it.
My choice, mix the 87 and the premium.
Fill up with either and then when you reach a 1/2 tank re-fill with the other. Note more than likely 1/2 tank gage reading is not correct!
You need to determine what 1/2 tank looks like on the gage, could be 1/4 or 3/4, or anything in between.
Then fill-up at that time with the appropriate fuel so you can maintain your approx 89 octane fuel.
Easy for me, once again I refer to my log to determine what fuel was last used.
At least in your area should be flat to rolling hills and your mileage should be better than those of us that live in mountainous regions.

[Pu241]

Interesting and it's worth a couple of tankfulls. I also presume one will not get that type of gas mileage with a lead foot. I never got over 30/31 but my driving style is not conducive to getting good mpg.

Changing just part of your driving style can help too!
On the highway cruising at 70-80mph isn't going to help you MPG wise.
Cutting back to 70-75 will help some!
But better is in city driving not hammering the accelerator from light to light.
Timing the light so you don't have to stop is better.
Sitting at a stop light, after the engine is warmed up, shut it off and restart if your going to be sitting at the light more than 10 second.
Check your tire pressure adjust to just below what the rating is on the side wall of the tires.
Or lower depending upon how much of a beating your willing to take because higher pressure tires will transmit more vibration from the road imperfections.
A few small adjustment can make a big difference!

Hey where are you located anyway?
Do me a favor and scroll to the top of the page and click "profile" and put something in the location field so we have some idea where your at.
Like I just learned that in Todd00 area he can't get reg 89.
So some geographical info is useful!

[elcamino1]

I to find that 89 octane or midgrade gives me the best mileage and the best performance.

[easywind]

I'm in the city, Manhattan and lowering tire pressures is not happening. I like my rims just fine.

[Pu241]

I'm in the city, Manhattan and lowering tire pressures is not happening. I like my rims just fine.

Lowering the pressure from the maximum rating on the side wall!
At maximum pressure your ride will be far more "active" than you might car for!
I suspect given the weather of late unless you have recently check your tire pressure, I'd be willing to bet it is well below the maximum pressure rating!