i got a truck not that long ago...maybe 6 weeks?(see sig) anyways...i run 87 oct. because it is cheapest. is there a reason i should run higher? i heard it is good to fill the tank with high oct every once in a while...but i do not know why. any info on the subject would be great. thanks.


A

 

come on guys...someone has to know some things.

 

There is no point in running higher octane if your truck runs fine on 87. Way back when, the premium brands had more cleaning additives and were worth the price for a tank or two. But now, EPA mandates make it so that all grades of gas have the same types of additives. All you get with premium gas these days is higher levels of MTBE, which raises the octane and reduces the total energy content per gallon. Expect 1 to 3 mpg less with premium over regular.

 

I have a 98' F-150 and my manuals says to only use 87 octane fuel and not to use a higher octane. Thats fine with me because it is cheaper. I like Texaco gasoline.

 

beastrider....

thanks for the info. you say it would give me a little worse gas mileage? does that mean a little more performance...or just a waist of money? thanks again.

A

 

You don't state what year model truck you have. If it is very late model, the electronic ignition system, specifically, the anti-knock sensor, might advance the timing more with premium, and this would give you better performance. But, if you have an older model truck, with a simpler ignition system, premium will make no difference.

See

http://www.faqs.org/faqs/autos/gasol.../preamble.html

fo everything you ever wanted to know about gasoline.

 

thanks for the link...but i did say what year. it was in my sig.

A

 

My experience with running higher octane in my '97 4.2L is that gas milage does increase by 3-4 MPG under normal, mostly metropolitan highway driving.

It's a heavy truck with a relatively small engine for moving so much weight so I don't expect the milage to be too impressive unless I'm on the interstate at a constant speed.

I don't have any problems justifying what I spend on fuel for my truck. Not even when it's over $1.30 per gallon. I do keep records of every tank of fuel though just to know how efficient my engine is operating.

I've also experimented with different fuels, spark plugs, spark plug wires and driving combinations to see how my milage varies.

Under the same summer driving conditions:

>91 Oct/FMS 9MM Wires/Bosch +4=18-20 MPG
>91 Oct/OEM Wires/Bosch +4=15-17 MPG
>91 Oct/FMS 9MM Wires/MotorCraft Platinum=16-18 MPG
>87 Oct/ FMS 9MM Wires/Bosch +4=15-17 MPG
>87 Oct/OEM Wires/MotorCraft Platinum=14-16 MPG
>87 Oct/FMS 9MM Wires/Champion Truck Plug=14-16 MPG

Although I havn't noticed any performance gains from a higher octane fuel, the MPG definately increase.

Without an aftermarket chip, the timing will not advance enough to increase engine performance but the 9.2:1 comprssion ratio is enough to burn the higher octane efficiently and increase the MPG noticably but more for ego than for economy as it pretty much evens out for cost verses MPG gains.

I now use FMS 9MM wires 87 Octane & Champion Copper Truck Plugs and get around 15 MPG and don't worry about it.

 

NOT!

Nice post, except the reason that you get more MPG is precisely because the timing has been advanced. You cannot "burn the higher octane efficiently" because in fact, it has less energy content per gallon than does regular. The 9.2:1 compression ratio permits you to burn regular without pinging... only a higher compression ratio can increase engine efficiency.

Looking at your numbers, it looks like you get about 2 mpg more per gallon using premium. Using your Motorcraft numbers you go from 14 to 16 or 16 to 18, an increase of 14.3 and 12.5 percent respectively.

Here in Houston, last week regular was 97.9 and premium was 117.9, a difference of 20 cents or 20 percent. So, even with improved mileage, it would cost me more to run premium than regular.

However, we have 93 octane here, and I think I'm gonna have to try your experiment and see what kind of mielage change I get.'

Thanks for the info.