Why? It's been beaten to death far too many times.

Use E10 if you like. Use E0 if you don't.

Your car might sees up to a 3% mileage/power drop with E10 vs. E0. No other effects.


Octane rating has nothing to do with ethanol content. Apples and oranges.

 

In terms of its octane rating, ethanol has a rating of 113. Fuels with a higher octane rating reduce engine knocking and perform better in cars that need a higher octane fuel.. Also, almost all gasoline in the US contains 10 percent ethanol. When you mix 10 percent 113 octane ethanol with 85 octane gasoline it increases the octane two points to 87 octane most consumers use. So the higher the ethanol content, the higher the octane. The octane rating for E15 (15% ethanol) is 88 octane and E85 (85% ethanol) is 108 octane.

Having said that you burn more fuel that contains Ethanol to go a certain distance than using E0 fuel.

 

And 91 AKI gas is still 91 AKI (and 93 is 93 etc.), irrespective of ethanol content. Why confuse the issue?

 

The above statement is true however saying that Ethanol content has nothing to do with Octane rating is not true since adding Ethanol to gas raises
its Octane rating.

 

No wonder the OP is still confused. ;(

 

Aha, the fuel mythology, cousin to the oil mythology. Yes, the octane in the fuel should match the demands of the engine. Under match, not so good. retarded timing at best,
holed pistons at worst!!! Not logical to do it.


OTH, higher octane than the engine demands is merely lightening the bill fold, for no useful purpose. Is Premium fuel cleaner than regular, I don't think so. But, caveat, I am only a gear head, not a petroleum engineer. I did know one, decades ago, he poopoo'd the idea. "our fuels are as clean as we can make them".


Top tier vs low tier??? Many come from the same refinery. Same basic fuel, but the additive package may differ.


Many brands around here, but only three refineries. Conclusions???


I'll top off my old Jeep today on Shell 87. Same with the Jaguar last week, each enjoys the fuel.


Way back in my shed, I have some fuel flex lines for 30's era cars. Would they survive Ethanol. Not for long. But, ethanol has been around for decades, so the flex hoses have been tailored for it. No consequence, unless one is reviving a really old car.


But, ethanol loves pot metal. Leaves a chalky compound that is the very devil to clean from teeny passages...


Carl

 

Deleted

 

So we're going to muddy the water by mixing ethanol, octane ratings, cleaning additives and world famine myths all rolled together.

I believe this sets a new record.

 

Please delete.. posted under wrong model

 

X type info is not really relevant to XJS.
At least the V12 cars with marelli ignition did in fact have a fuel strategy link to enable a change from low to high octane fuel. I cannot comment on the 6 cylinder cars.
My 6 litre runs very happily on low octane fuel.

 

My error.. I was in the x-type section and must have somehow inadvertently crossed over into the XJS in my search.. I'll be sure to watch that before I comment.. thanks..

 

Just to add to the confusion. I bought a1998 Lincoln Town Car ( 4.6 liter V8) in 1999 with 20,000 miles on the clock. It now has 102,000. Lincoln states premium fuel. I used regular fuel 87 octane since purchase with no ill affect. Car performance perfect good acceleration no knocks.

 

I know this is an old thread, thay more or less was revived for no reason, but I'll put in my $ .02 anyway..

​​​​​​The higher the grade, the better the quality. Higher octane fuel burns slower, resulting in a more complete burn. This creates better efficiency and results in less deposits left behind, which can over time be harmful to performance.

These being luxury vehicles designed to run on premium fuel and intended to be maintained by dealers and deep pockets - it makes sense to run premium only. Yes it's 60 cents a gallon more, but the cost difference on say 1 tank a week isn't going to break anyone, and you tend to get better mpg.

As far as the average vehicle, yes you can run 87 just fine, it won't hurt the engine, and the computer will compensate.. However to maintain a clean engine I still run premium in everything I own. The fuel injection system in my '00 Bravada is notorious for clogged tips, and better fuel prevents issues.

Regarding the dreaded ethanol.. I hate it, avoid it when I can, etc.. It's the other reason I run premium I'm everything as it's the only fuel sold locally without ethanol. That being said if your vehicle is new enough to have been designed to run on ethanol mixed fuel then it should not matter. If you have older vehicles that were not set up to run ethanol then I would try to avoid it - to ensure the longevity of fuel system components.

 

An old thread resurrected with the same old myths regarding Octane Rating!!!

Quite a few people seem not to have any background in science.

 

My owners manual for 1990 V12 , clearly says 91 OCTANE ONLY. I use 100% gas 91 octane.
My 1999 SL500 Mercedes also says 91 octane only.
The rest of my vehicles get 87 octane but they all get 100% gas, even my mowers,chainsaw,weedeaters, etc
No ethanol period.

 

Not quite sure what you mean....but octane rating and 'quality' are not the same thing. There are high quality gasolines out there with only an 87 octane rating


Better fuel, yes. But cleanliness is determined by the additive packages, not the octane rating



The owners manual for my 1985 Jaguar specifically says that E10 is OK. I'm not sure how far you'd have to go to find any prohibitions against it.

Personally I think the ballyhooing about E10 is grossly overblown....but it's like motor oil discussions. Or who makes the best beer

Cheers
DD

 

The English, Doug, the English!

 

Nonsense. I've never found English ethanol to be one bit better than American ethanol !

Cheers
DD

 

It was explained to me that higher octane fuel provides a more complete burn, I guess I connected the dots to quality on my own. I stick with 91 but as far as where I fill up I base it off of the mileage I get from the fuel more than if it contains ethanol or not. Only 1 of the 3 stations local to me that sells ethanol free fuel actually gives me better mileage. If someone has science to bring to the table instead of commenting on a lack of scientific backround - I'd be happy to learn something new.

 

Heh heh, I, for one,am incapable of explaining any of the science. I have only a 12th grade education and struggled to pass first year chemistry. I still get queasy at the thought of "specific gravity" or "moles"

However, the general consensus is that E10 yields about 3% less energy. Not sure if that's the correct way of stating it but that's the gist. So, to me, it's plausible that some report better fuel economy by using non-ethanol but, at the same time, often wonder how a 3% difference can yield a measurable result amid so many other driving variables.

Others with more scientific expertise will chime in

Cheers
DD