Downunder, Subaru EJ22s are run on "standard" 91 octane unleaded fuel. I understand that in Japan the octane rating on which they run is as little higher though I don't know whether there is any difference in Janapese and export engines.
I run My EJ22 import on 91 octane and it seems happy ($1.24/litre today). Today I find the local petrol station is selling "standard" unleaded with 10% ethanol ($1.21/litre today. There is pressure to use this fuel in Australia though when it was first introduced there was strong objection on technical grounds.
Can anyone comment on the wisdom and effect of using a 10% ethanol fuel in an EJ22?
Stations here use up to a 10% ethanol mix here in the winter time. Sometimes the attendant can tell you the exact amount if you ask but otherwise you're left guessing.
Not sure how the ethanol affects octane rating.
It can give you up to a ~10% distance decrease per unit of fuel burned, depending on ethanol content. (Yay, just what everybody wants!)
It does not decrease the end cost of fuel.
Supposedly the alcohol helps prevent frozen fuel lines, or at least lower the freezing point, while at the same time improving wintertime emissions, but I've only heard this as rumor. (If you have to burn more fuel to traverse the same distance, have you really improved emissions any?)
10% or less of ethanol is not supposed to be enough to cause problems with fuel seals in cars that were not designed for it. (How would any average joe be able to figure this?!)
Local spec 2.2 and 2.5 are both designed to urn on 91 ULP. In my experience to date, our previous 2.2 coped with 10-18% ethanol (about 3 tanks out of 4 on average) for 70,000ish Km without anything going funny, but fuel consumption was down a little on 91ULP. Price at the time more than compensated. 95 E10 wasn't available to compare and premium didn't make *any* difference to performance or consumption, but cost more! 2.5 currently runs ok on 91ULP, 91 or 95 E10, or premium ULP. Fuel consumption is *slightly* lower on 91 E10 than std unleaded, up to 1Km/L lower on 95 (no I don't know why wither, but it's consistent) and no different on any premium we've tried over the last 80,000Km or so. Best performance / consumption / cost compromise seems to be Shell or BP 91, then 91ULP, then
91-92 E10. The other two options we've given up on unless there's no alternative on the day. Cheers
I use in my Forester in US because that is all that is available here. In addition to above comments, fuel with ethanol has stronger solvent properties and before gas station conversions, tanks must be cleaned or may contaminate fuel. It also cannot run through pipelines for same reason and must be trucked from refinery. Supposed positive environmental effects are dubious and have been foisted on us by big agribusiness who profits vastly from its use.
Been using 89 octane E10 for years in my 95 Legacy. I do think the ECU wasn't design to use it optimally because I find that I _seem_ to get a sudden boost of performance and economy if I put in the odd tank of straight unleaded.
I haven't tried to do a scientific trial to verify whether this is actually true or just my perception (influenced by weather, how much crap is in the back etc...)
A theory is that E10 burns more completely leading to less crap going past the O2 sensor which causes the ECU to compensate by running the engine a little too rich. Could be a totally bogus theory - comments?
Its promoted as being safe for all cars. There are some who worry that, if E85 si not safe for older cars due to fuel system component damage, wouldn't E10 just damage components more slowly? And you may experinece lower mileage for a coupla reasons. Ethanol has only about 60-70% the BTU/volume as gasoline, and it may 'fool' the car's computer into running slightly richer.
To me, the bigger problems are those outlined here;
Where did you get that? Every source I can find, including ethanol producers, claim a decrease in mileage. The "best" I have seen is a claim of a 2% reduction when using 10% ethanol and the worst I have seen is a claim of 15% reduction when using 10% ethanol. Ethanol has less energy (BTU) per unit volume than gasoline so you would expect a decrease.
Charles, I think you and I are saying the same thing. Perhaps I misworded or am just plain confusing, but was trying to say "a decrease in miles per gallon" in a manner that miles and kilometers didn't get in the way for the folks outside of the States. (-; I find it less confusing than liters per kilometer at any rate, or whatever it is the Canadians are using at this point! And I hope nobody accuses me of being a proponent of ethanol.
The worst part is that a lot of the ethanol comes from corn, which is produced using nitrogen fertilizers, which in turn have been produced from natural gas... a fossil fuel. The resultant demand for corn has pushed up world corn prices as well.
Not many people are aware that the grains that form the bulk of their food (or feed the animals that are the food) is grown the same way. Your bodies are also running on fossil fuel, folk! And even if society survives the melt-down when the oil runs out and transport becomes 10x as expensive, there'll be a worldwide food shortage because of the lack of fossil-fuel fertilizers, so 90% of the land used for grain will become unusable.
the O2 sensor which causes the ECU to compensate by running the > engine a little too rich. Could be a totally bogus theory - comments?
Hi,
What I KNOW about ethanol would fill a thimble, while what I THINK I know would fill volumes. So I'll just toss some ideas out and folks can chew on 'em...
We KNOW that:
Ethanol has a lower heat content (BTU/unit weight) than gasoline. This results in lower fuel economy (miles/gal, km/l, l/100km, however you like to rate it.)
Ethanol is VERY clean burning relative to most other common fuels. Note it's used in marine stoves, where there's a close quarters, poor ventilation problem more often than not. People don't get "gassed" as easily w/ it as if they were using propane or some other liquid fuels.
Ethanol doesn't vaporize and burn as well at low temps as some other fuels.
Now, put this into an auto engine, and it means you'll get lower fuel economy, fewer emissions (at least of the type we're used to. Fingers have been pointed at formaldehyde as a byproduct--I dunno. Frank L? Anybody?), and good low temp running, esp. below freezing, isn't a selling point.
As for the O2 sensor and the ECU, my understanding of most common O2 sensors is they run on heat. They sample the exhaust gas temps, and if the mix is running lean, it'll be too hot, and the sensor will tell the ECU to toss some extra fuel in there, richening the mixture. If the temp's too low, it's too rich, so the sensor calls for less fuel (all of this, of course, after the various other sensors have had their input: you can't call for a leaner mixture on a cold engine and expect "driveability" to be part of the picture.)
So... IF the exhaust from a "gasohol" mix IS actually cooler than that from a straight gasoline burn, I suppose the O2 sensor could make a call for a richer mixture. I'm not sure the actual "cleanliness" of the exhaust is a player, especially at a light mixture of ethanol, such as E10.
As I said, the last ideas are from the volumes of "I think I know" stuff, so I stand to be corrected as necessary!
In the air force in the 60's we used to test for icing inhibitor for jet fuel, and it had to be 7%. There will always be microscopic droplets of water in fuel from condensation that won't settle out, and can freeze, and the ethanol is supposed to mix with the water.
the O2 sensor which causes the ECU to compensate by running the > engine a little too rich. Could be a totally bogus theory - comments?
Formaldehyde, I don't know but would not consider it much of a problem. Incomplete combustion of ethanol might give acetaldehyde. But, mixed with gasoline, other decomposition products would probably overwhelm those just from ethanol alone.
The original oxygenate requirement was engineered by big agra-business like ADM to benefit farmers. Lower pollution, particularly in winter was claimed but refiners said they could meet it without ethanol. In response to the government mandate, they satisfied the oxygenate requirement with MTBE which is cheap and also increased octane which ethanol does not. Unfortunately as ppb MTBE in drinking water causes bad taste and environmental groups jumped on it and had it banned.
In this thread, also, I'm not sure of commercial status of a Subaru E85 vehicle for US but Subaru one. In DE where I live, there is exactly one E85 station about 30 miles from here ;)
In my 98 US Impreza with a 2.2 and manual trans, I get a 20% reduction in fuel economy with a 10% ethanol mix. 26mpg vs 32. I no longer use ethanol fuel in my subaru for that reason
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