Ethanol /Premium Gas Mix 93 oct vs 92 Premium ethanol free
 

Good Morning,

New member/New Boxster owner. Glad to be part of the family!

I live on a county border in Wisconsin and basically have the choice of the two blends. Should I run a 93 octane premium with Ethenol or go ethanol free but settle for 91 or 92 octane based on the gas station.

I apologize in advance if this question has been covered, but search did not turn anything up on the forum.

Buy the highest octane you can find (93) from the busiest (fresh) national brand gas station in your area. It's as simple as that. Don't worry about ethanol. If you want to fill up with ethanol free 91 octane prior to winter hibernation (plus StaBil) that would be fine.

Don't worry about ethanol IF you know that it has been regularly used in the car since new. If you switch to ethanol after yrs of regular gas, the ethanol will loosen up any sludge on the bottom of your gas tank. Guess where that sludge goes? All thru your fuel system and clogs everything along the way. New cars or cars that have used ethanol regularly won't have the sludge so no worries. But older cars that haven't used ethanol will be trouble if you start using ethanol (a tank in a pinch won't kill you).

The loss of 1 octane for non-ethanol fuel will be worth the lack of headaches the above creates. Your car's computer will figure out how to map to the 92.

What about adding Octane Booster to the lower quality Gas?

I use Octane boost about every other tank, and try to use a Higher Octane Premium on the in between. Has to do with my location and trying to lower fuel cost and maintaining my performance.

I would love to have that choice and run 91 ethanol free gas..

I regularly run ethanol free 91 on my Porche and Audi and lawn equipment; they run great. I am also located at high altitude so 93 is not readily available.

No it's not, gasoline has far more BTU's than ethanol & thus more power. Octane rating is a rating of resistance to ignition not power potential.

I am not aware of any fuel in Wisconsin or Illinois that is ethanol free and 92 octane. Unless you are taking about a marina, race track or airport.

I made no statments about BTUs or power. So, I don't know why your making this response to my answer. What is your recommendation to tlzkaasen? And what do you dispute in my answer? Have you ever purchased fuel in Wisconsin or rural Illinois and understand the situation?

I want all those British Thermal Units I can get :D

The 92 octane ethanol-free gas will make more power than the 93 octane ethanol blend, if that is a factor for you. Probably not enough that you probably would notice any seat-of-the-pants difference, but it would probably show on the dyno.

As a person in the gas business, here are two cents about BTUs. Ethanol contains 92,000 BTUs per gallon, regular no lead comes in at 132,000. Personally, I have run both 93 E10 and 90 REC Gas without an obvious difference in performance. As a previous poster pointed out, octane and energy are not one in the same. I do have serious misgivings about ethanol in general and storage with ethanol blended fuels in particular. Phase Separation can be a real issue in a fairly short period of time. Our suppliers claim a 90 day shelf life on blended fuels. If you do not have access to pure gas for storage, modern additives seem to be pretty effective in delaying it.

Ethanol...
 

..is hydroscopic--it absorbs water.

If you have a reliable supply of pure gas, even if it is a couple octane points lower, run it.

Your knock sensor will detect the lower octane and pull ignition timing, so no damage will occur. You will only notice the torque drop, if you notice it at all, below 2,000 rpm.

Ethanol is just bad.

Run Shell pure gas if you can, or buy some pails of "T4" from VP Racing Fuel

Here:

https://vpracingfuels.com/product/t4/

I've run this in my Boxster, Ducati Monster with hi-comp pistons, RC51, and GSX1250FA. They love it.

:cheers:

I think this juice might be the same as a product called KARTANE. It had a splash of Methanol. I used it when Karting. Unusual exhaust smell!

What I am running in my PBS is Shell's 93 E Power, and the Shell Diesel which has the highest Cetane which is around 48. Adding Power Service in the diesel fuel also helps boost the power.

This old thread came up in a Search, so rather than create a new discussion, I figured I'd just tag on.

Filling up my 986 S fuel tank this a.m., I find that my local Sheetz now offers me a choice of fuels:

a). 93 octane with 10% ethanol, and
b). 90 octane with No ethanol.

My 986's owner's manual clearly calls out 93 octane minimum with the comment also that ethanol fuel use is fine. So that part's quite clear, and I've been using it exclusively to date.

But in my case, this car does not receive regular use - over the past couple of years, I've only driven maybe 500 miles each summer, only about 2 tank's worth / year. And the car sits idle for maybe 6 months at a time during our winters. So there's a lot of time where the fuel just sits there in the car's tank, waiting patiently for something to do.

I dutifully throw a bottle of Sta-Bil into the tank each and every fall, prior to winter storage, and so far I've not observed any fuel-related issues upon the spring start-up.

But after lots of anecdotal warnings about the effects of long-term ethanol deterioration (including some right here in this old thread above), I am now beginning to believe that the use of 90 octane non-ethanol fuel is in my long term best interest, those missing 3 octane points notwithstanding.

Any fresh thoughts since the last post (2018) in this discussion, either pro or con?

Cheers - DM

First of all…
 

…Drive the darn thing.

Sitting around is the single worst thing for a vehicle.

If you really aren’t going to drive her, then definitely fill up with “Pure Gas” or “Rec Fuel.”

There is a web site, Google “Pure Gas”, that will show you pure gas stations around you. If you live near a body of water that attracts boaters, typically the gas stations near the boat launches sell pure gas.

Dump a bottle of a “PEA” fuel additive into your tank, fill up with pure gas, and drive around for about twenty miles to mix it all together and get it into the fuel injectors and cylinder walls.

The only fuel additives out there that have the PEA in amounts that work are “Driven Injector Defender” and “Carb Defender”, Chevron Techron MARINE, Gumout “Total Fuel System” and Redline Fuel system cleaner.

But you should really drive her.


Better to be driven into the ground, than to rust to death.

I know that it’s blasphemy, but you could just use 87. Cuz knock sensors are a thing. Or so I’ve heard.

Since tetraethyl lead and MTBE are now illegal, the major octane booster added to our gasoline is ... ethanol.

I've never understood how high octane can be achieved without an additive, and most places that offer ethanol free gasoline state 87 octane or something. I'd really like to know how a high octane ethanol free gasoline can be produced these days. The real test might be in a vehicle without octane automatic adjustment.

Stop thinking about “octane” and start thinking about anti knock index (AKI) which is what you see on the pump. It’s the average of the research and motor octanes.

An overview of the materials used to increase AKI may be found at https://en.m.wikipedia.org/wiki/Antiknock_agent

All above is good info….
 

…..ethanol free fuel will have lower octane.

Like someone posted above, fill with 87 and nothing bad will happen.

The knock sensor will prevent knock.

You’re not driving the damn thing anyway, so why worry about losing a few horsepower?

Just fill up with 87 “Pure Gas”, drop some fuel stabilizer or the PEA additives I listed above, and get on with your life.