EvanZR1

CA is 91 only due to their emissions regulations and CARB. If people would only use the octane that's needed, it wouldn't be a big deal, but there is an emissions impact if you run higher octane than what's needed, and my understanding is this is why CA stops at 91.

Kingtal0n

Scientist here. I work with 100% ethanol, methanol in my research. The ethanol in gasoline is the same as the ethanol in vodka. It doesn't go bad sitting in a glass container because the container is sealed properly.

If your device like lawn mower has a tank which is sealed up fully it will be like the vodka, fine in storage for any length of time. They are rarely sealed up fully however.
Modern vehicle fuel tanks intended for flex fuel are sealed using check valves and a emission device which regulates the vapors of the tank in one way or the other. This can keep alcohol fuels in good condition for many months.


Over long periods of time however no matter how good your fuel tank is, there is something else that happens


Yes the water from air can gradually work its way into the fuel right through the fuel tank walls over time. The EPA sets the limit I guess



So, gasoline can get out. Water can get in. The water will 'effuse' a bit faster than gasoline based on some general calc


Water is so small

270picometers can fit easily over time, bouncing around in substrates/tissues/materials

Well what does this mean to us performance enthusiasts. We have to use a big picture to understand the pro and con of this situation.
Pros alcohol:
1. alcohol is superior to gasoline in almost every way as a fuel except its energy content (lower miles per gallon but better at everything else)
2. alcohol is safe to drink whereas gasoline is not e.g. alcohol is not only superior in almost every way its also safer to be around in general

Cons alcohol:
A. Alcohol will draw water from air more quickly than gasoline and will suspend that water more easily allowing it to come into contact with objects in the fuel system and corrode them. This is an issue for vehicles originally not intended for alcohol content fuels. Metal will corrode quickly and certain rubber-like materials can simply melt in alcohol.
B. Fewer miles per gallon
C. A specific con of E85 fuels delivered to the gas station sometimes contain biomass which can clog fuel filters. This isn't a con of alcohol but rather the delivery system of alcohol to your fuel tank. Just like gasoline can be contaminated "Bad Gas" the alcohol can be "Bad Gas" but in a different way e.g. clogging filters and pumps instead of pinging the engine.

So this is it then. Alcohol is an incredible racing fuel and safer for human contact than gasoline. Alcohol is a racing fuel superior to many leaded racing fuels because of its latent heat of vaporization influence which helps control EGT and CHT (cyl head temp). Therefore we PREFER to use the alcohol whenever possible.

When is it a bad idea to use alcohol?
-when the fuel system is not compatible (you better be sure about that)
-when you plan to let the fuel system sit for extended periods of time without a proper SEAL on the fuel system to prevent air contamination of water

With enough of a fuel system venting leak (improper fuel system containment sealing) and enough alcohol content the fuel will be troubled by water from the air.
Even with a proper sealed fuel system given enough time both gasoline and ethanol will still eventually go 'stale' or 'bad' or collect water in one way or the other. Alcohol is just better at it.

I would advise use as much alcohol as possible but when it comes to storage and vented fuel system to avoid the alcohol for long term storage.

Lights ZR1

Shell is no different than Mobil, Sunoco, or any other Top Tier fuel. They all come from the same place. The additives are added by the station. And they all use the same stuff. It's marketing and nothing more.

I also religiously used Shell on my ///M cars and until I realized how stupid the cult is, and suspected the gas was causing an issue on my last car. Sure enough, Mobil stopped said issue.

Much like "Xpel" film, another dumb cult, and mediocre product. Suntek and Stek are miles better.

Yes, 94 E10. I only use Sunoco 94 now, for the knock protection.

Z0HS1CK

Could be coincidence but that was my experience.

I actually use exxon for the M3 wthout issues. It's my 2 z06's that i use shell v-power only.

Drew888

The octane in CA fuel was reduced by the manufacturers to improve throughput and reduce cost. The fuel used to be 92 and went down to 91. I have several friends that work at CA refineries and production is an issue.

In most states fuels come from the same place, same pipe. There are some states where the refineries have pipelines to the stations or to their own facilities. I believe in TX many of the chevron stations carry chevron produced products.

Many of us have a substantial amount of knowledge on this topic and offer a short prudent answer so these don't have to turn into chemistry lessons. It's to laborious to always have to cite several pieces of proof to satisfy the nah sayers.

There is a reason that the non-ethanol fuel is produced. It is more stable. These engines will run on 91oct. Yes, they will make less power. For most this is not an issue and is a way of life in states like CA.

Most agree using the ethanol blended fuels is ok. If you had a non-ethanol option, it might be a consideration for storage or as I had mentioned previously a limited use application.

Here is my opinion about alcohol fuels. In racing applications methanol adds a lot of extra work. Even E85 on the street is mediocre. My preference if all were equal (octane, cost etc.) would be to use straight gasoline. Ethanol from corn is bad for us because we are using the soils macro-nutrients for transportation. We are competing with our vehicles for energy.

Kingtal0n

But it isn't equal. With gasoline a stock engine will need to tap out around 600rwhp to control EGT and piston stress but on E85 no problem 1000rwhp cool as if it has oil squirts.

Flex fuel means no hassle with changing fuels. You just put gasoline all the time unless you happen to feel like using alcohol instead. It is just more options, more choices, more flavors. Why stuck with ketchup all the time when you could sometimes have a dry honey or bleu cheese sauce from a normal gas station pump you found.

I don't see any argument against flex fuel due to cost. As a performance car escalates in output and capability, tires are extra cost. Flex fuel is extra cost. Turbo is extra cost. You pay to play, that is the name nature of the hobby.
The flexibility of engine output config evolves from the fuel you have access to, better fuels more flexibility with output configs. Flex fuel broadens that availability window without pigeon holing you into a specific fuel quality, you can keep the engine stock or whatever you want the alcohol is more compatible overall but gasoline is still an option. Alcohol once in a while to pass emissions and clean the intake valves and pistons free of carbon. Its a great solvent with engine cleaning ability worth investigation. As long as you do everything yourself and tune yourself of course there is little added cost over any other comparable performance installation. Where the fault line occurs - it looks like a dramatic scale expense if you don't know how to tune yourself and setup properly on your own knowledge. A flex fuel sensor and a flex fuel compatible sequential EFI computer together run the cost of an expensive dinner for gen3 LS applications using stock engines up to 1000rwhp