Preferences for Ethanol-based Fuels

[LaszloT]

Folks,

I'm running mid-grade in my 2009 STi for day-to-day use, and use either Premium or Ultra 94 for track events. However, I'm interested in what you prefer. Here's a little primer as a context to start though.

Aside from Sunoco, the industry has standardized around E10 (10%) for Regular, no Ethanol for Premium, and since Midgrade is a blended, it becomes E5. This means that when you fill with Premium, you are NOT getting Ethanol.

Ethanol is actually good for fuel systems, as it helps clean and remove water. All Sunoco fuels have Ethanol, including the coveted Ultra 94.

Cleaning Properties

Initial use of Ethanol fuels tends to clean engine residue and this ends up in filters. Gas stations had this same issue upon conversion, but this happened in 2006 in the key urban areas, so it's behind us for the most part.

This is not an issue for new engines or storage systems, and the good news is engines are cleaner as a result.

No More Water

Ethanol-based fuels (unlike most fuels) are hydroscopic (readily abosorbs moisture). This requires some special procedures in storage and has created some concern when not done adequately.

The consumer concerns that exist are based on Ethanol's sensitivity to water in storage. This is some times referred to as it's 'stability'. There is no issue for engines with nearly undetectable quantities of water dissolved in fuel. Gross amounts of water into storage tanks (from a rare fillbox leak, for example) will stratify the fuel an it will be identified by daily operational checks, and in that event the fuel will need to be replaced.

On the positive side of things, there will be no water in your tank if you occasionally run Ethanol fuels, as tank vapour space moisture gets consumed with the fuel in normal operation.

Customer Preferences

General preferences I hear about are to avoid Ethanol for marine and small engine appications. Marinas have a greater exposure to water and often were not as knowlegable about the properties of Ethanol when it was introduced, and it caused concern. They also have a winter storage cycle that is unique, but this does not need to impact preferences, as Ethanol has the same stability of other fuels, stored properly (shelf life of many years).

That being said, I'm interested in your preferences.

What are you running?

[tashko]

I avoid using Ethanol laced fuels as much as possible for fuel economy.

When I drove the Talon to distant events, I'd run low octane w/o Ethanol and then fill up with 94 on the last tank. Makes the drive a little boring since you can goose it but saved $$.

[STeveD]

I try never to fill under what the car is tuned for, especially turbo cars.
I don't like getting to an event without full ECU learning on a higher octane if it is for competition.

I run Shell 91 preferably in Pugsy because the responsiveness is noticeable and the zero ethanol content fuel economy benefit. That's a car factory tuned for 87. I could run 87 if I commuted to save some money, but fun is the priority in both of my cars.

Unless it's E85 tuning for performance (which again isn't economical except in track cars), I avoid 10% ethanol added fuels like urine on the floor of a bathroom stall.

[Lloyd]

The Prelude I run 94 on to be careful, since nothing in the car is stock anymore.

The vette just gets 91. Shell 91 would be preferable for fuel economy, but I think Shell charges more for their 91 than competitor's E10 91, correct me if I am wrong.

Not really sure which makes more power at a fixed fuel flow & air flow rate (E10 or E0), but if I ever figure that out I will use that one.

[LaszloT]

Prices for premium fuels are typically 8 and 13 cpl above the street price for Midgrade and Premium in the urban areas.

Shell and Petro are 9 and 15 at the moment, and Ultra 94 is 18 cpl above the street price.

The energy content of E10 is 2% lower than E0, and this is the biggest tradeoff I see. E5 has a 1% lower energy content.

Shell's Premium fuel (V-Power) has a good reputation for better mileage.

All fuels from major oil companies have a proprietary additive to differentiate them in their marketing, and the Top Tier Fuel designation is a minimum level of detergency additive.

[JoeT]

I wish there was 94 Octane without E10. Like the others, unless it's e85 for performance (Not economical for daily driven cars) If given the choice I would avoid using ethanol. I'm sure with today's technology, there exists additives and refining methods that can bring up AKI to 94 while maintaining an additive package with appropriate detergent qualities to keep an engine happy.

[BryceD]

After discussing with tuning shops, I was told that P-C 94oct with ethanol will make more power than Shell 91 without.

Therefore the car was tuned with 94, and that's all it gets.

The (stock) Forester get's 91, Shell if it's nearby for better mileage.

[Lloyd]

With fuel control and plenty of injector ethanol content is great if you don't care about fuel economy. And a higher octane on a knock limited engine is always good. Even on a NA engine E85 is likely worth a bit of HP.


Reading the original post again, I'm not sure if I would run low octane on a turbo motor with a reputation for blowing up easily.