hotrodln

OK so my local gas station used to just sell 93 with ethanol. worked great in the car no knocking....now they have 91 with no ethanol. I'm thinking about trying it out...but it costs more than the 93 up the street....anybody with experience trying the two? I know i'll be buying the 91 for any of my cars with carbs...the ethanol gas really screws up anything old that i have....but i wonder if it has any negative effects on the 09..

jrose7004

I don't use any ethanol gasoline's in any of my cars. I use 91 octane 100% gasoline in my Vette and don't have any knocking issues.

elcajonblvd

I would pick no ethanol.

also I only get gas at big name gas stations ( mobil, shell etc;...) so I know im getting tier 1 gas and it seems I rarely see "no ethanol.

hotrodln

yeah i'm no fan of the ethanol...it's ruined the carbs on my snowmobiles and my 62 caddy carb is always getting crudded up....

Gearhead Jim

81k miles on our 2009 using 93 oct ethanol from any Top Tier station. Still runs great.

In theory, you don't need the 93, just 91. But some people have scanned their engines and say it's pulling timing with 91 on a hot day, so 93 might help a bit.

The fact that modern cars are made to tolerate ethanol doesn't mean it's the best thing, but it's about all I can get and no problems on any of our cars. Just buy from one of the many Top Tier stations (Google Top Tier Gas)

Vito.A

The problem with ethanol is the Stoich ratio (ideal air/fuel mix ratio) is 9:1 and gasoline is 14.7:1. Your car is tuned for 14.7 (except for wide open throttle). So as you introduce methanol to the fuel mixture, it runs lean.
Add to this the problem that ethanol is hygroscopic (absorbs water from air) and will corrode non coated parts and hoses.
Even at 10%, its just not an ideal fuel for these cars.

ls1121

So it is either Pure Gas or Gas with moonshine. I prefer Pure Gas but here it is like $1 a gallon more...thieves and I will not pay it. When I was living in Roanoke Va. the Pure Gas was only .35 a gallon more and I tried to use it exclusively but since I moved back to Charlotte seems these gas stations just want to rob you. I asked one guy where his mask was, he looked puzzled.

hotrodln

The no ethanol gas is about 40 cents a gallon more than regular. (87)...but only about 20 cents more than 93 with ethanol around here.

HOXXOH

Be happy that you have a choice. Only 91 E-10 is available in AZ, short of 100 racing at $8/gal.

ls1121

OK I found an Exxon today with 93 @ $3.15 in Charlotte, my usual gas station in SC is $2.39 with Moonshine added. Seems like a lot of money just to have the refinery do less work. the regular w/ethanol is $1.98.

acheman8

Ethanol is rarely added at the refinery. It is typically blended at the distribution terminal as it is being loaded onto the tanker truck for delivery to the service station. That is also where the fuel is additized with the brand specific proprietary additives.

Also, ethanol blended gasoline is cheaper because the government (which mean your and my tax dollars) are used to subsidize the corn farmers and credit the gasoline blenders up to $1 per gallon for every gallon of ethanol they add to gasoline.

Next, a refinery is like a huge aircraft carrier. The processes to turn crude oil into gasoline are finely tuned and optimized based on the feedstock and the desired output product slate. The gasoline that is blended with ethanol is actually LESS octane, since adding ethanol (at about 109 octane) boosts the overall octane rating. You don't change that base octane rating of the refinery output with the flip of switch. In other words, a refinery can make 91 octane gasoline to sell directly to the consumer, or make 88 octane gasoline to blend with ethanol (which is cheaper than the gasoline in the base case due to subsidies) to make a finished product of 91 octane gas. Which choice sounds like "less work"? Also, think about the supply and demand. Due to government mandates on renewable fuels, the demand for ethanol blended fuel in the US is orders of magnitude greater that unblended. What do you think the refiners want to optimize their production for?

Finally, todays engines are designed to operate fine with ethanol blends up to 10%. The seals, elastomers and non-metallics are all designed for ethanol blended fuel. Is it less efficient? Yes. Is it bad for older engines? Yes. Is it bad for boat engines, which are exposed to copious amounts of water? Yes. All else being equal would I personally purchase 93 octane fuel without ethanol given a choice? Yes. Am I concerned running ethanol blended fuel as essentially my only realistic option? Nope....

icntdrv55

As far as knock, octane rating is octane rating. Doesn't matter whether the gas has EtOH or not. You car should run fine on 91--that's the octane recommendation from GM. As to whether "gas-a-hol" is harmful for your engine, again….your car is designed by GM to use blended fuel with up to 10% EtOH.

The main issue with ethanol-containing fuel is it's propensity to absorb water from the atmosphere (during rainy, moist conditions) which can result in phase separation of the gas and EtOH/water component when they reach a high enough concentration. This occurs most often when the car is sitting for long periods of time with some amount of headspace in the fuel tank. As long as you are driving your car regularly and using up the fuel in the tank and refilling on a weekly basis, it shouldn't be a problem. Prior to storing it away for the winter, I make it a point to run my tank mostly empty and refill with pure gas (non-EtOH fuel). If you live in an area of the country where you can drive year-round, it shouldn't make a difference and you'd be wasting your money on the more expensive pure gas, IMHO.