merchauser

Since I bought my 1990 last spring, I have only been using non ethanol 90 octane gasoline.

Current fuel lines are original, and new ones are on my to do list.

A bit pricey at nearly $4.00 a gallon, I am wondering if I am just wasting money and might it be better to use 93 octane 15% ethanol gas?

would I pick up anything using a higher octane fuel?

is ethanol a real enemy of our cars, or is this just a bit of minor hysteria?

comments???

FredR

Ethanol helps boosts the overall octane of the gasoline blending pool but reduces the amount of energy liberated as ethanol has a lower calorific value.

docmirror

I wouldn't use anything with 15% Eth in it. Try to find a premium with 10% max Eth. The 90 has knock sensors, and presuming they are working right, won't allow damage to occur with lower octane fuel use. You might loose some power, but the engine will be protected.

merchauser

10% ethanol 93 octane is available at a distant station; but is it "better" for our cars to have non ethanol fuel? do I benefit with 93 octane but loose with the ethanol.

Like all of us, just would prefer to do the best for the car.

This car has been on the road for 27 years and has survived whatever fuel previous owners have used, and its running fine. Pretty sure, that its past history did not include anyone analyzing what fuel to put in...lol

FredR

When do you intend to do your fuel lines- after the car has burnt to a cinder? If those things are original then by now I would strongly suggest you are on borrowed time and them some.

As I understand some folks reckon that ethanol has a negative impact on fuel hose life- I cannot comment on that as I have no experience using the stuff but on my 90 S4 the fuel lines were rock hard before it was written off [by accident] some 12 years ago! On my current 92 GTS I replaced them about 3 years ago and it was not a day too soon.

docmirror

Opinions on Ethanol differ depending on the person's economic and political persuasion. I am of the opinion that adding Ethanol to our fuel is a boondoggle and trillion dollar subsidy to the two largest ag conglomerates in the world.

One thing I know for certain, any amount of Ethanol in the fuel supply causes problems for cars built before about 2004/5, when the Ethanol mandate got serious. Cars made before 2005 or so have trouble with fuel systems. Most fuel pumps have been redesigned with different materials in them to handle the fuel, but it's still an issue for many older cars.

Just my 2 cents, but non-Ethanol fuel, of the proper octane is the 'best' thing for our cars. Best simply means it conforms most closely to the fuel spec in use when our cars where designed and produced. !0% Ethanol is a lower standard, and 15% Ethanol should be avoided.

YMMV, objects in mirror, pro driver closed course, and may cause **** leakage.

GlenL

The latter.

928S MN

Wow Non-Oxy premium for nearly $4/gal!

Where do you live? I just filled up this weekend and only paid $2.83/gal.

I've always wondered what kind of power these motors could make utilizing E85 with the correct sized injectors and a compression ratio that could take advantage of the E85's 105 octane rating.

fiatrn

Ethanol has caused me some serious troubles with some of my cars, but all on cars with carbeurettors that I don't drive to0 often. When you don't drive to 0often, the ethanolized gasoline seems to accelerate fuel line breakdown, especially on older-specced lines.

On the car I drove before my 928, I saw my mileage drop by 20% when my city switched to ethanol. The car had a multi-carb setup in the valley of a V8 engine, and the ethanol would boil out of the carbs on shut down, cause terrible starting troubles on hot days, and was generally the single biggest frustration driving the car. When i could find non-ethanol gasoline, all those troubles would stop.

On the 928, I don't have any of the hot start problems, but the fuel mileage does seem a bit worse when I am driving on E10 than when I find non-ethanol gas - which is on road trips and outside the city I live in.

Replace your fuel lines regardless. They are a wear item. Then, fill the car with what you can. e-Zero is best, E-15 is the worst. Per gallon, ethanol has less energy, so the car will get less power and less MPG using higher ethanol gasoline. I've seen calculations that show the "cleaner" burning of ethanol is entirely erased by the fact that you must burn more to make the same power, but I have not done that math myself. If you drive the car frequently, the ethanol will probably not damage the vehicle - and definately not damage it as much as if the car sits for long periods.

Adk46

There'd be a lot of 928's with fuel system problems if ethanol was even slightly harmful over 10+ years. Now, if you're planning to let old gas sit in your car under a tarp for ten years, that's a different situation.

Out of caution, and because it's readily available around me, I go for the non-ethanol stuff. It's only 91 octane, but I believe that's enough to avoid triggering the knock sensors.

You'll find people around here who think that ethanol-free 91 octane is "better" than ethanol 93 octane. Perhaps in some ways, but not knock-resistance; stated octane is the result of a fairly direct measurement.

I also favor it in my new Macan since the 4-cylinder model only requires 91 octane and it has a higher energy density.

FredR

The only way a motor is going to make more power with ethanol as a fuel is if it has forced induction. The calorific value of ethanol is only about 2/3rds that of gasoline. Force feed more air and fuel and then you can take advantage of the octane rating and make power but most folks who force feed motors prefer to run a lower compression ratio and a big blower. The problem with gasoline is getting the octane number up and if that is not possible then timing has to be pulled back and that costs power.

Difficult to get gasoline with an octane higher than 98 RON, pure ethanol has an octane rating of about 113 RON.

Red Flash

To point 1: I agree wholeheartedly. But since the federal government subsidizes so many activities mandated at the behest ? of lobbying groups, I'll take my subsidies. It seems no political party or person can stop this crazy system. Apparently not even Trump.

To point 2: I do not hear of near as many fuel line fires from my 928 friends in Europe who in the meantime are numerous. Not even in Spain or Italy where it is hot. Ethanol is bad for fuel lines unless you buy GB's fuel lines and eliminate the intake pump methinks.

polecat702

Use Marvel Mystery Oil, you won't have any problems. I pick up a quart of it when I travel, and my cars love it.

I just replaced the internal pump in my 89, along with the external. The original hose on the internal was still good till I twisted the thing in half. The pump itself was seized. !0% ethanol, won't hurt older fuel systems. E 85 is a different story.

FWIW, my car is forced induction.

The Forgotten On

The owners manual for my 81 specifies that E10 is perfectly acceptable and that the fuel system was designed for it in mind.

Unleaded fuel has gotten much better since our cars were originally built so it shouldn't be a concern if you use E10 or not, as stated above avoid E15.

You only lose 4% of the energy in a gallon of gas using E10 compared to E0 so it shouldn't affect running that much in a semi modern fuel injected car like the 928.

Either way replace all fuel lines including the soft lines in the rear of the car. Old lines are a fire waiting to happen.

hacker-pschorr

Alcohol has been used in fuel since the invention of fuel. There are many different types of alcohol used in fuels. Up north we dump alcohol into our tanks to keep them from freezing.

The difference is, e10 is regulated to have up to 10% of ethanol. Before such regulations you could of had 10% of various other random alcohols in the fuel - especially in winter since those blends contain more to keep fuel lines from freezing. Even "Ethanol Free" gas has alcohol in it. Any negative effects on fuel lines from ethanol will apply to other forms of alcohol.

So no, ethanol is not "bad" for fuel lines or gas tanks. If your lines fail running e10 they would have failed with "e free" fuels.

Why your friends across the pond don't see "as many" failures.....without concrete numbers, miles driven, storage conditions, car history etc..... such a comment is meaningless. Different parts of the US have some downright dirty fuel, it's possible whatever crap they put in reformulated gas chews away gas lines, which would have nothing to do with the 10% ethanol.


Random example. The 97- Jaguar engines are "known" to have a major issues with the cylinder coatings wearing off. Time has shown the main culprit was fuels high in sulfur, something not found in every region. Certain major cities (that just happen to sell a lot of Jaguars) are known to have fuels high in sulfur:

http://www.popularmechanics.com/cars...ar-nikasil-v8/

Not all fuels from state to state, or even city to city within the same geographic area, are the same.

Sulfur levels in gas was not federally regulated down until 2006. God only knows what this substance in higher levels does to 30 year old fuel lines.....


Point is, there is a lot more to fuel comparisons around the glove and even smaller regions than just ethanol.