I know there are many threads that talk about what octane to run. The consensus always it Premium. I totally agree with the advantages and also better for your engine, o'2s, etc. But, I have been running my disco 2 on 91 which is the highest you can get around me locally.

My question is:

So the local stations I've been buying gas have 91 premium and regular with a 10% ethanol blend. Their mid-grade(89 octane) is Ethanol free. Should I run the mid-grade since it doesn't have ethanol in it or stick with the premium? Its also .40 a gallon cheaper.

Little bit from web search. Ethanol contains about 10% less energy per gallon than gasoline does. Since most gasoline contains 10% ethanol, you will get about 1% worse mileage using gas with ethanol in it.

So I figure I have potential to save cash, increase mileage a tad, and better care for the engine internals being ethanol free. Or will the lower octane outway the benefits of Ethanol Free?

 

Just so you know, mid grade is a mixture of regular and premium, gas stations only have 2 tanks in the ground, when you pump mid-grade you will hear the pump clicking back and fourth between the two tanks in the ground thus mixing the two grades to make one.
So if the regular has 10% ethanol, and the premium has 10% ethanol...mid-grade also has...

 

The energy that is released and fuel economy isn't really what you should be concerned with imo. The higher octane rating decreases the likelyhood of pre-detonation in the cylinder head. This is especially important when it is hot outside. You should run the premium.

 

Spike weird the label on regular and premium both have a sticker that says contains 10% ethanol. But the mid grade 89 non ethanol is its own pump and states ethanol free so I was thinking different tank. They did not have ethanol free until it seem most stations had to replace there in ground tanks in fl. After they replaced there tanks this was an option and stand alone pump. Not sure on this one maybe Ill ask gas station owner as its a private owned Liberty Station.

I will continue running premium at this point.

 

Depending on where you live getting 89 or 90 oct with out ethanol is more common. Here in FL I have a few stations That offer pumps without ethonal so we can fill our boats. It is cheaper than filling up at the marina.

 

EBG...Where in Tampa do you find fuel w/o Ethanol? Thanks pal!

 

Talked to station owner defiinately a sole tank and pump for 89 Non Ethanol. Might try it. Is 1 Octane point really a difference my owners manual says gasoline CLC or AKI octane 90 or 92. Although I understand what Wilson was saying about the higher octane to avoid detonation and that might be a downfall of 89 compared to 91. Which I understand cause I run 100 octane on higher boost in my turbo T/a to avoid and definately can tell when crappy gas is in.

But, Im not towing or hauling just highway driving. Is the -1 point octane going to cause detonation or negative affects? I'm new to these engines and not sure of there so called flexibility on things so you guys tell me?

Also I have a scan tool to monitor live data would the vehicle not pull more timing if detonation was present from lower octane. Also could monitor short and long term fuel trims to see if theres any variance in what o2's are reading, especially in long term. Maybe I can monitor a tank Premium vs tank 89 Ethanol free?

Should I just drop the idea or is it worth a try?

 

I recently had a chance to try 91 octane non ethanol premium at a local indy station in Idaho while I was on a trip... I was shocked and amazed at the difference it made in both smoothness and power in my 03 4.6l. My truck LOVED that fuel, even at one point in octane less than I normally run. I also noticed better mileage, however I did not have a chance to actually measure it, I filled up, drove 330 miles and still had over 1/4 tank indicated on the gauge... which is not normal.

I normally run Chevron premium 92 octane exclusively which in the Seattle area has 10% ethanol.

This station i later found gets its gas from the local Chevron jobber, not sure exactly what it was though, other than non ethanol. at that station it was .02 more than the 92 octane premium with ethanol.

In Seattle non ethanol is really hard to find. one station I know of carries it near where I live and that is also an indy station but they charge .50 more than the ethanol version. Which is why I had not tried it yet.

I'm still not going to pay .50 more to get it at the current prices however I'd say removing the ethanol makes a huge positive difference.

Let us know what you find. Its worth trying a tank I'd say.

 

Download the iPhone app called 'pure gas', it will tell you where you can get ethanol free. I just use Sams club 93 in the rover, and since my boat stays at little harbor marina I just get gas there for the boat. $4.60/gal for 90oct eth free.

 

I know this has been discussed before, but; technically the owners manual says use 91+ and "lower octane may be used at the cost of economy and power" or something to that effect. It doesnt mention that damage can occur at much lower octanes (89, 87 etc). So my question is, would the lower octane fuel really be bad for the truck? I run 93 because they only have 89 or 93 around here. Running 89 would save me a decent amount if it were ok.