Which octane do I use?

[Daleford]

I am dreading the gas mileage that I am going to get on an upcomming trip with my 4.0 litre, automatic 2009 Ranger ext cab 4X4. I have been to the dealer for any updates on the computer, but I am wondering about which gas to use. I generally use the lowest octane because of lowest price. However the lowest price might not be the best buy. Your opinions??

 

[superds]

Do not pay more money for fuel that has an octane rating higher than necessary unless you need it to combat predetonation, such as in a high compression engine. Your engine is rated at 87 octane at most altitudes and even lower could be used at high altitudes, like in the mountains.

The only way I will pay more for a higher octane is if the 87 octane contains 10% ethanol and the higher octane (such as 89) contains 0% ethanol and is only a few cents more per gallon. The theory being, ethanol decreases fuel economy by a small amount and switching up to a higher octane with no ethanol should yield a fuel savings. I'm still testing this theory; I record all my fuel usage including information such as where I filled, price I paid, what fuel was used and date so I can track my usage and find the optimal combination to yield the most cost effective solution.

 

[doorgunner]

Despite the arguements.......All I know about octane is this: My Harley motorcycle (9 to 1 compression) goes 200 miles on 93 octane.......it goes 150 miles on 87 octane....different brands of gas cause the mileage to vary by 20%...

As for a lower compression truck engine, the difference in mileage is related directly to the "kick" the engine has on accelleration...(the performance variation is REALLY noticeable on the Harley).

Conclusion: (the quality of the fuel varies a lot...even when buying it from the same gas station....kinda like your favorite bar---depends on who's mixing it)....


ohhhh yeah......if I'm going to be driving in town a lot...I'm gonna use the cheapest gas...they all get the same mpg's in a traffic jam!

 

[Irokranger93]

I like your theory doorgunner ,I made a has the same variety fuel consumption (atv) 87 -89 -93 and I got the same thing you more mileage with the 93 octane, but we did not always need this species in our region its use...
sometimes my engine belch with not enough octane

 

[jeffw920]

87, only use higher if it starts pinging...which if it does the issue is more likely excess carbon rather than the 87

 

[xnickitynickx]

Yeah, you should definitely stick to the octane that your engine was rated for. Unless, as previously stated, it has a crapload of enthanol in it.

 

[JohnnyO]

Newer vehicles have knock sensors but there is still a window of available timing advance in the computer. Basically if it doesn't knock on 87, then running 89 or 92 octane won't make any difference. That said, different parts of the country get different gas at different times of the year. Where I live we get the crappy oxygenated fuel in the summer and I've had vehicles that run better on 89 in the summer.

There are add-on tuners you can get, guys on the Sport Trac board like the XCal, where you can get an 89 economy tune that will allegedly get you better mpg but you have to run 89 octane.

 

[Surrey]

10% ethanol blend will typically result in aprox. 2% lost fuel economy.
That being said, there has been a study done by the University of North Dakota that shows e20 and e30 blends being much closer (and even exceeding in some cases) to standard gasoline mileage.

http://www.rhapsodyingreen.com/rhapsody_in_green/files/optimal_ethanol_blend_level_study.pdf

Realistically, the best way to get better gas mileage is to do all those little things that add up...
Proper tire pressure, accelerate lightly from a stop, dont overload the car,(100lbs can equal 1-2% mileage) dont speed, and use cruise control if available to maintain constant speeds, and dont touch the A/C (although I dont think that will be much of a problem on this trip. lol)

 

[85_Ranger4x4]

Fuel varies too.

Here 87 is straight gas, 89 is E10 and premium is straight gas.

I have been experimenting with 89 (10 cents cheaper than 87, 20 cents cheaper than premium) in preperation for this summer, so far I have noticed little change in milage in town in my '150.

 

[shane96ranger]

I use 85 on my 96 and have been getting 17-18mpg the past 3 tanks. We have ethanol mixed in most stations gas' around here; the stickers at the pump say "up to 10%". There are a few that are advertising ethanol free gas now.

 

[cammeddrz]

allow me to add to this discussion that higher octane than is necesarry will cause a loss of power on paper. but many guys psychosematically (sp?) think their rig runs better on higher octane. at one of the shops i worked at we tested this on a dyno....zero gain on a gsxr-1000 between 89 octane, and 110 octane. but a .2 hp loss (which was within margin for error)

 

[rusty70f100]

In my area (CF Iowa) 89 octane with 10% ethanol is usually about a dime cheaper a gallon than 87 octane. So I run that. I've also advanced the base timing 2 degrees to take advantage of the extra octane. So far it's worked well, as I still get very good mileage on it. Last trip I took, when it was about 30F out, I got 25.4mpg round trip. That was mostly highway at 55-60mph though.

What I have noticed is that gas from different stations will give different mileage. I find the "top tier" gas at Kwik Star to be about the best for mileage. It could be gas pumps calibrated a bit differently though.