Gas: Ethonal vs Top Tier - And related questions

General Discussion
#1

So I just wanted to post and get some insight/opinions from members on here about gas selection and options available.

Since I’ve owned my Audi, I’ve only put in top tier 93 octane gas (used to put BP in, but now only use Shell if possible). I figured gas is one thing it’s not worth cheeping out on and I want to get the most from my car. However, with the ethanol debate rising, I was curious what some thought about using gas with no ethanol additive but that aren’t at a top tier provider. And it sounds like there’s the potential it could go from 10% to 15% in the future, which doesn’t sound promising or healthy for most motors.

Finding gas that does contain “up to 10% ethanol” is very difficult around me, but ironically, there is a gas station right across from my office that offers only “100% gas, no ethanol” (one of about ~4 stations in the Nashville area). I filled up my Jeep there the other day just to see if any difference was noticed. The gas was about 10-15 cents higher, but at 10% of ~$3.50, that’s 35 cents when comparing ethanol vs gas.

Just curious what some thought. I know some are lucky enough to have the top tier offer ethanol free, but that’s not an option around me. I’m not extremely knowledgeable on the topic, but did find it interesting watercraft as well as airplane motors should NEVER run gas with any ethanol added.

Also, while on the topic. Other than cats being destroyed, how does race gas that is leaded vs unleaded affect things. (Obviously I’ve only used unleaded). I just ask b/c the tracks I’ve gone to sometimes offer race gas of variant octanes, but it’s almost always leaded options and just didn’t know how some cars could run it and others couldn’t

#2

leaded fuel will poison the O2 sensor membranes

EtOH free fuel will result in better fuel economy, more molar enegry content

#3

^Yea forgot to mention the O2 sensors about leaded fuel. But what are the advantages/reasons that is so prominent in performance situations and even aircraft motors (low lead etc). Just curious as I know little on the topic. Guess I need to google more.

On the EtOH fuel, how do you view that in the Audi’s and other performance based cars vs fuel from the name band premium places?

#4

I think the Count once said that the ethonal does not affect us at all because it is made up for with timing ro something like that. We have all 10% ethonal in Chicagoland but up in Wisconsin they have a lot of no-ethonal gas but it’s only 92 octane. I notice no difference with either

#5

Shell 91 = no ethanol (that’s there top ocane)

Sunoco/Petro Canada 94 = with ethanol

Makes you fast…and makes your gas needle go down fast too. I average about 5-7% better fuel efficiency with the 91 no ethanol from Shell.

#6

wait, so no ethanol is better?

#7

Yeah it’s better but I don’t think we really know how much better

#8

94 with ethanol is better. moar faster is moar better.

although the negative effects of ethanol on fuel efficiency are annoying, I really don’t care relative to better performance I’m afforded (vs buying no ethanol 91). The ‘drying’ effects of ethanol on the other hand that prove to be a problem with carb engines may also have some kind of long term effect on car engines…but I haven’t seen anything about this. Everyone used to worry that the ethanol would dry out seals and lead to leaks of various sorts. Not sure how legit that fear is.

#9

Interesting about the shell 91 Saki, unfortunately that’s not an option down here. Everyone in TN/AL/KY for the most part is 87/89/93 and every name brand station I’ve been always has the sticker “all gas may contain up to 10% ethanol”

#10

The concern about ethanol in marine applications is that it absorbs the water that accumulates in the fuel tanks causing missfires and all the things that water in gas would usually cause. We had this issue with our boat. Filled it up at a non-marine gas station off the highway which was 10% ethanol, and 2-3 weeks later we started having issues with it caused by the gas. Not a big deal really - just had to add a couple cans of seafoam. Marine gas is so expensive. A good 40-50 cents higher than regular, and it’s always 89 octane.

I don’t see how that idea will apply to carbeurated engines. How the eff do you spell carborated?

#11

I think it’s the opposite…it dries everything out.

Ever put hand sanitizer on your hands, alll wet and gelly…then after 15 seconds your hands are dry? Alcohol.

#12

Well in marine applications, it draws in water

#13

I think you’re talking about the same thing…it draws water out of the fuel and seperates it. It also draws moisture out of just about everything rubber.

#14

10/15% grain probably makes a very small difference, but e85 to gas there is a more noticeable difference. Not sure about how it behaves in our cars…

http://www.edmunds.com/fuel-economy/e85-vs-gasoline-comparison-test.html

#15

E85 would be good for the supercharged guys, but IIRC, the higher octane of E85 only means less power on the n/a cars

#16

H3C-H2C-OH … H-O-H

strong hydrogen bonds on each, they attract… ever pour 1 measure of pure etoh into 1 measure of pure h2O? You don’t get 2 measures of fluid once mixed. The water ethanol interaction is very interesting.

as far as a fuel e10 v pure dino its a wash imho, the etoh provides better cylinder cooling (allowing more timing advance) the dino stuff has better energy content

#17

yeah it dehydrates, then evaporates and pulls the water up with it

#18

hmm lucky no one caught you, thats a big deal up around here… the extra cost is probably all tax and no one comes down harder than the tax man

#19

Nobody cares around here. There’s a gas station right across the street from the launch ramp that people alre always filling their boats at.

#20

Carburetor. That’s how my phone wants to spell it. Although my phone also wants to spell tire so what does it know :smiley: lol

+1 with saki about the petrol up here. 91 No ethanol = further, 94 = faster.

I agonised for a while over 91 vs 93 tune as the Shell 91 is the most convenient for me. But then if I wanted convenient or economical, I would’ve got another TDI.