Is there an advantage?

[Boondocker]

Is there a mileage advantage to be had from using premium fuel? I have always wondered and a new thread by Toastys dad got me thinking.....

[87MH]

Originally Posted by Gen Disarray

Is there a mileage advantage to be had from using premium fuel? .....

Only if your engine is set up with a computer to advance the timing to an optimal ignition advance point just before "pinging" occurs - the "premium" gas is sold with a higher octane (ping retardant) rating.

If no such automatic timing device there will be absolutely no difference in gas mileage between an 87 octane gas and a 140 octane Aviation Fuel.

Note that without a computer constantly monitoring the engine it is very dangerous to advance the timing too much beyond manufacturers suggestions....an internal detonation (ping) could lead very quickly to a "kiss of death" for your motor.

So, a quick answer to your question - IF your engine is set up to take advantage of an increase in power due to an internally regulated advance mechanism and IF the compression ratio remains constant - then yes, the mpg could be marginally improved, to the extent that a more aggresive timing advance would benefit.

Both Premium and Regular (High and Low Octane Rating) gas contain the same BTU's per gallon. One of the reasons that gas is less efficient when compared to a Diesel Fueled engine is that there are more BTU's per gallon of Diesel compared to a gallon of gasoline (it weighs more, therefore there is more hydrocarbon to combust in a gallon of Diesel). One other reason of increased mileage (efficiency) of the Diesel is the incredibly high compression ratio present when the diesel/air mixture starts to burn.

[Boondocker]

Originally Posted by 87MH

So, a quick answer to your question - IF your engine is set up to take advantage of an increase in power due to an internally regulated advance mechanism - then yes, the mpg could be marginally improved

My engine is a 1991 ford 302. So do I get this right, using premuim gas can be bad for the engine???

[87MH]

Originally Posted by Gen Disarray

My engine is a 1991 ford 302. So do I get this right, using premuim gas can be bad for the engine???

No, I did not mean to infer that at all, I simply stated that, given the engine will not advance the timing to the "ping point", the mpg will not change simply because you run "Premium" vs. "Regular" through the combustion chambers.

Quite the contrary (to being bad for the engine), there may well be additional "cleaner" additives in the premium gas as compared to the regular. Unfortunately, until the retailer gives a thorough listing of all of the additives in each of his grade of gasolines (and that will NEVER happen) you will never know for sure if his claims (if any) to a "cleaner engine" are true or if he is just selling you a crock of crap for a hefty adder on each gallon of gasoline.

Rest assured, you will not damage your engine by running a higher grade of gas than what the manufacturer calls for - you will just, in my opinion, be paying a bunch more for a gallon of gas than what you need to.

One important caveat - IF your engine calls for a certain grade of octane rating, you are certainly taking a chance of damaging your engine should you decide to purchase a gasoline with an octane rating BELOW the manufacturers spec.

[Toasty's Dad]

hi,

so as the guy who reported the mileage increase, i'm not quite sure what to make of all this. we seem to have done about 2 mpg better while running on premium.

our mileage varied a fair amount from tank to tank, but the 2 mpg was averaged over the roughly 6 tanks it took us to get out west (regular), and the 6 it took to get back (premium), with a total distance of about 1200 miles each way. if anything, we used the AC a bit more on the way back, as temps were 100 in TX/OK.

so from what you say, i either must have this advance feature in my engine's control system, or the "improvement" was due to some other factor. i'll grant that chance may be responsible, since i can't guarantee that we drove EXACTLY the same in each direction.

or perhaps a change in engine operation? we _did_ have an oil change in NM, right before our first tank of premium.

cornfused,
jon

[Boondocker]

I wonder if wind was a factor....

[myoung]

Hummm. Ohio to New Mexico is uphill. New Mexico to Ohio is downhill. It's easier to walk downhill than uphill.

[87MH]

Originally Posted by Toasty's Dad

...so as the guy who reported the mileage increase, i'm not quite sure what to make of all this. we seem to have done about 2 mpg better while running on premium. ....so from what you say, i either must have this advance feature in my engine's control system, or the "improvement" was due to some other factor. i'll grant that chance may be responsible, since i can't guarantee that we drove EXACTLY the same in each direction....

I pulled this quote from the Honda Ridgeline website -


The i-VTEC® engine enhances the effect of VTEC® on the V-6 engine by adding variable timing control, or VTC. VTC is a hydraulically operated system that controls the timing of the chain-driven intake camshaft, advancing or retarding it during the intake cycle.


I would have to assume that if they are advancing and retarding the cam, the ignition timing is also changing.

I would further say that your engine was operating efficiently and therefore was able to produce an extra +/- 20% mileage increase for about a 10% price differential in premium vs regular gas.

The BIG question is whether or not it will be able to do the same thing 150,000 miles down the road.


Anyway, glad you had a good trip - thanks for sharing your mileage experience here.

The Honda Ridgeline looks like a macdaddy tow vehicle for a trailer in the 4000 to 4200lb range.

[Toasty's Dad]

>I would further say that your engine was operating efficiently and therefore was >able to produce an extra +/- 20% mileage increase for about a 10% price >differential in premium vs regular gas.
>
>The BIG question is whether or not it will be able to do the same thing 150,000 >miles down the road.

Oh probably not, but you've made me a happy man today, Dennis.

Thanks,
jon

[Boondocker]

How do you tell if your motor is capable of benifiting? Is it a safe bet that an old (1991) 302 will not?

[Alumaholic]

Click and Clack, the "Car Guys," advise that all "other factors" being equal, using premium fuel will not improve fuel economy. Otherwise, they reiterate, some of the advice given in this thread, i.e. if the car manufacturer says you must use premium, you must use premium or risk damage to your car's engine. You will not hurt an engine designed to burn regular by using premium, but you will be wasting money.

Toasty's Dad must have had some "other factors" contributing to his reduced fuel consumtion. This happened to me once the week after I purchased my 2003 Z-71 Suburban 5.3L with 3.73 differentials. I got 14.7 miles per gallon towing our 2000 Safari 27 from Albuquerque to Benson, AZ. I was delighted with my purchase, but it never happened again.

[Wabbiteer]

yakkity yak blah blah I seemed to have written a book blah.

My daily driver & tow vehicle is a 1999 F150 4x4 5.4L auto with 87k miles.

Minnesota has mandatory 10% ethanol and I loose 12% highway driving with ethanol blend so I'm sensitive to mileage. With zero petroleum deposits in the state Minnesota will still have some fuel if the pipelines shutdown tomarrow so we grudgingly support ethanol; nowadays the discount for alcohol blend makes our fuel prices "appear" a little less painfull too.

When I get out of state and my highway mileage of ~15mpg goes to ~17mpg with less oxygenators added (ethanol) I try and find gas stations that have a competitive price and narrow spread between fuel grade prices and fill up with premium if it is not labled "ethanol added". My mileage jumps to ~19+ if I ease back out onto interstate, blend smoothly and drive the tank empty.

17 to 19 is nearly 12% so if the premium for premium is below 10% I can usually save money burning premium. At $2.80 a gallon for regular 87, 91 octane (ethanol free) for $3 would be a deal for me.

Towing my AS at 55mph and smooth higway driving gave me almost 14mpg using premium - I started calculating dollars per mile and saw a spread between $11 to $17 dollars per hour cruise with speeds & fuel octane changes. Hate being an obstacle in the right lane but money is too tight to be fuelish, just smile and wave like its great fun and get even at the fuel pump.

One thing it DOES do nicely is reduce (change) engine vibrations, lowering the engine shake amplitude lowers my fatigue level when driving straight through on long trips. I have severe tinnitus and being trapped for hours in a moving vehicle irritates tinnitus untill its pure misery - additional sound like radio or wind whistle stiffly lowers my stamina, burning premium is somewhat soothing over road-trip of 1200 miles (drive 6 / sleep 2 works well for me coast-to-coast)...
~

[2airishuman]

hi fuel sniffers........

most owners manual will specifiy octane rating.......which dictates fuel type.

the audis for example specifiy 91-93 so premium is the ticket....using lesser octane rated fuels doesn't hurt short term (because the drivetrain will retard timing as the octane rating goes down....but hp and mpg decline too.

toasty/gen disarry......we are waiting 4 ya hat the rally!!
lookin g in your owners manual for the answer.

now the bigger issue is what about after ethanol is mandated in fuel......

premium will NOT have ethanol added while retualr does.........

cheers all
2air'

[Boondocker]

Originally Posted by 2airishuman

toasty/gen disarry......we are waiting 4 ya hat the rally!!
cheers all
2air'

I head up in the morning

[safari57]

My wife's BMW 740I gets 3 to 4 MPG better when running premium versus lower octane fuel. It is noticeable over a long journey although the actual costs incurred are up due to the use of the more expensive fuel. We do notice that the car "seems" to run better with the higher octane but that could just be me.

My TrailBlazer doesn't seem to notice a diff. It sucks it up regardless, get the same mileage, which is not very good at the best of times although surprisingly it's as good as my friends new KIA equivalent (heh, heh) which is a pain for him. When towing the TB gets horrible mileage, worse than my '57 Pontiac with a 455.

Barry

[Bob Thompson]

An interesting thought, about 2 years ago, the gasoline pipeline from El Paso to Phoenix, Az. ruptured out in the desert, shutting down supply of gasoline to the city and surrounding area. Everybody was out of gas in every grade. Few people picked up on the concept that that one gas line supplied the regular, mid-grade, and premium to the city and all the vendors. One type of gas arrived at the batch plant. That gas was given anti-knock additives and detergents to make the various grades. Every gas station got their fuel from that one gas line. The base product was the same at the QuikyPiky as at Union 76.

For the record, one of the refineries here in Corpus Christi is set up to produce all of the gasoline for one of the major cities in New Jersey. Again, the QuikyPiky gets the same gasoline from the same source as everyone else in the city.

[Boondocker]

Originally Posted by Wabbiteer

.......
Minnesota has mandatory 10% ethanol and I loose 12% highway driving with ethanol blend so I'm sensitive to mileage...........
When I get out of state and my highway mileage of ~15mpg goes to ~17mpg with less oxygenators added (ethanol) ............. My mileage jumps to ~19+ if I ease back out onto interstate, blend smoothly and drive the tank empty. ............17 to 19 is nearly 12% so if the premium for premium is below 10% I can usually save money burning premium. At $2.80 a gallon for regular 87, 91 octane (ethanol free) for $3 would be a deal for me.
~

So am I correct in thinking that while towing ( esp at higher elevations), it would be wiser to go preimum over regular (assuming ethanol additive) for the extra oomph? Does anybody know of a state by state break down of ethanol additives? or has it become ubiquitious now?

[jcanavera]

Usually unless your vehicle is E85 rated, the 10% ethenol mixture is the maximum blend you can run. I've not seen any station offer anything higher than 10%. The down side is that ethenol does not provide the equivalent mileage of pure gasoline, so it's not unusual to see that some premimum gas without the ethenol additive might give you better mileage.

As far as higher altitudes go, I think I remember at one time seeing higher altitude Colorado gas stations selling 89 octane as their low end product.

We have several oil terminals in the metro area and I have seen all brands of trucks show up there. From what I have been told the only difference between brands is the additives. In many cases the tanker trucks carry the additives and the mixing of those additives occurs during the tanker fill up. Other than that they are all buying the same base grade gas.

In my part of the state the environmental emission regs require that we use blended fuels in all grades during the summer months. Interestingly enough if I go 50 few miles east into Illinois many stations sell their ethenol blended mid grade (89 octane) fuel for up to $.05 per gallon less than the unblended (87 octane) regular.

Jack

[Wabbiteer]

Ethanol raises octane - In Iowa I've seen they used to offer non-alcohol regular for up to a 10¢ premium over the mid-grade containing 10% ethanol, however with the MTBE additive ban the demand for using ethanol as replacement has driven the price up so the cost difference may be moot point these days.

Assume there is some ethanol in all gas, it acts as a drier via carrying it through water-excluding filters. There certainly is Ethanol in Premium gas, blended gasolenes include tolulene, benzene and a dozen other solvents depending on spot prices or availibility.

Its hard to find but Minnesota has a pure petroleum Super-Premium that is intended for off-road recreational vehicle use only. The product commands a steep price premium and is provided to maximize safety when our weather can become life-threatening whether in power craft on the water or winter time sports.

When last in Colorado I used the lowest octane (85?) as the prices where 30-40¢ higher then I'd just seen in Missouri and Kansas - definately slow on the spot-market price adjusting in Colorado from what I remember. I'm sure its all justified but sure looked like gouging to me...

[Boondocker]

Originally Posted by Wabbiteer

........Assume there is some ethanol in all gas, it acts as a drier via carrying it through water-excluding filters. There certainly is Ethanol in Premium gas, blended gasolenes include tolulene, benzene and a dozen other solvents depending on spot prices or availibility.....

Now I am more confused than normal . In an eariler post I understood you to say that the ethanol in regular gas was resulting in poorer performance compared to premium. Was I incorrect in this understanding, or is it simply a matter of the percentage of ethanol between grades?