10% Ethanol vs. Ethanol Free Gas

Zat_Zuma

My little research showed that 5% ethanol gave 5% less gas mileage and 10% was 10% less mileage.

Worked out to 2.5 mpg on the Challenger on 91 octane fuel with 10% ethanol. Same price as Shell 91 and 10% better gas mileage........ no brainer for me which fuel to buy.

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binary0x01

What I've noticed is I get better gas milage with 76' 91 than shell vpower... me thinks one waters down their brew a bit less...

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LMBmikeZ

glad to hear shell doesn't want to change it to!


That's a crazy difference for gas mileage! though, it is a no brainer which gas to use in the Z! Since day one with my 40th(bought new 000015km on delivery F.O.B.!) it has only seen Shell 91 ethanol free gas I bet if I looked at all my receipts 90-95% of the time it was filed at the same shell

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chops

as do i. i get consistently better gas mileage with 76's 91 octane over shell's 91 octane. about 2-3mpg each tank.

GrandZ45

Not an expert on gasoline nor a mechanic or even a Z owner yet (ordered), but what I learned about gasoline as an amateur recreational pilot agrees with Southark's post earlier. The alcohol increases the anti-knock index and therefore the octane rating of the gasoline but decreases the energy and increases problems with water.

The main problems in aviation are the lower energy content, the effect of alcohol on gaskets, seals and fuel lines not designed for it, and the attraction that alcohol and water have for each other. Many airplane engines are high compression engines that require higher octane ratings to avoid detonation and pre-ignition in high power operations (as in take off when the trees at the end of the runway can get close really fast). Takeoffs in small airplanes are full throttle maximal performance operations. Every bit of rated power is demanded so the lower power production of ethanol is a safety issue. Detonation can destroy the engine. It is also more likely when the engine is hot and the recommended action is to cool the engine by increasing speed (they are air-cooled) and reducing throttle. Avgas still contains lead as the anti-knock agent. Small airplanes sometimes sit for weeks unused. The air in the unfilled space in the tank contains moisture that may condense into the fuel on cool nights. Over time this can put enough water in the gas that it can cause problems--like engine failure and crash on takeoff. If the gas contains alcohol, the water can combine with the alcohol causing it to separate from the gasoline and create a large layer of water-alcohol sitting at the bottom of the tank.

Having said all that it just makes sense to me to prefer alcohol free fuel if it is available at the octane rating that the manufacturer recommends for any engine, especially if the fuel will sit there for a long time. More so in winter. The condensation problem can be countered by keeping the tank full instead of nearly empty. The less air space in the tank, the less water vapor will be available to condense each night. I gather that some Z owners use their cars only recreationally rather than daily drivers. It also makes sense to, if one must run fuel of a lower than recommended octane rating, to keep rpms and engine temps down and, if you value your engine, to not forge ahead if you think you hear knocking.

I have one vehicle that can sit for weeks unused. After some fuel problems, I began toping it off with ethanol free fuel before leaving it to sit. But the fuel is of the recommended octane rating so I am not compromising in that regard.

Not the place to rant about the ethanol racket but if one adds the information about reduced gas milage to the available data about fossil fuel requirements to produce ethanol, it is sort of obvious to any who care to look. Nuf said.

LMBmikeZ

I like your comment and would say

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2011 Nismo#91

I'd go with the cheaper Florida Law prohibits the sale of Ethanol Free in cars. For off road use its legal and should be cheaper since you shouldn't be paying road tax on it. They are probably doing what diesel pickup drivers do, buy home heating oil and run off of that and avoid the DOT tax and making a killing in profit. Or they are flat out lies.

"Florida RFS (Renewable Fuel standard, March 2008) required MANDATORY 100% blending of ethanol for public supply of gas by 12/31/2010. Exemptions exist for fuel used in aircraft, boats and watercraft, fuel sold to a blender, or used in collector vehicles, off-road vehicles, motorcycles, and small engines. View Press Release and House Bill 7135, section 103 of the Florida Statutes.

Florida law requires gas pump labeling with an E10 sticker when ethanol is added to gasoline. Sadly, several stations that advertise E0 ethanol-free gas, actually are selling E10! Many that sell E0 inflate price per gallon by far more than it costs them."
Florida - Florida - Ethanol Renewable Fuel Standards & E10 Laws

SeattleLion

Just thought I would chime in. I have been using 92 octang ethanol free gas for over 2 years. My Z got from 1 to 3 extra mpg without the ethanol. Also ethanol-free gas stores better as well. This is important for my emergency generator and lawn tractor. I am a total convert to non-ethanol gas. I have had no problem with water in my gas line or tank, btw.

2011 Nismo#91

I'm all for ethanol free gas, it's so much better, there was a reason gas suppliers didn't put it in themselves till the government (tax payers) subsidized it and states required it. It's more expensive, needs more of it to go the same distance, absorbs water, and breaks down rubber parts. Unfortunately it doesn't exist in the NY/NJ area.