10% ethanol gas has 92% of the energy (BTUs) of 100% gas
google it and do the math -- ethanol has about 78,000 BTU per gallon and gasoline is about 115,000 BTU per gallon
hard to see how come the mileage would be the same with a lot less energy per gallon
my experience in a former car (2007 Civic) was that 100% gas gave 38 hwy mpg and 90% gas gave 35mpg
that's driving the exact same 150 mile round trip that was mostly highway and filling up at one of two stations a mile apart -- one that had real gas and one with 10% ethanol gas
Oh just cruising down the interstate at 70 to 75 MPH. I failed to mention I got the 6 auto.35 MPG?? At what speeds?
Thats the highest MPG Ive ever seen from the Eco and A6. Ours has never got over 33.2 and that was going about 71 over a really flat road.Oh just cruising down the interstate at 70 to 75 MPH. I failed to mention I got the 6 auto.
I agree also, not saying it can't be better but not likely. Consistant 32.5-33.5 at 68 on flat ground with no city driving. One trip we did get 34.5 but that was not going over about 63.Thats the highest MPG Ive ever seen from the Eco and A6. Ours has never got over 33.2 and that was going about 71 over a really flat road.
1-If the ECM is retarding timing, you are losing power. I was told by a two techs that the car will run a little more timing with 89 and higher. If I recall it says this in the manual too. For the $3 a tank I will toss it in....I'm not gonna cheap out on $3.As to the original post 87 is all you need, if you have pinging it's either really bad gas or the computer is not retarding the timing properly. Run hi octane long enough and it will leave enough deposits eventually raising compression enough that it would possibly ping on 87.
Not the case anymore with all cars. My wives old Pathfinder said right in the manual that regular was recommended, but using a premium fuel will increase performance and is recommended for towing and maximum performance. The 3.6 benefits from multiple ECU timing tables too, not sure about the 4.Car and Driver did a comprehensive test some years back and talked to a lot of engineers. If your car was designed to run on 87, then there is zero benefit to running a higher octane (89 or 92 or whatever.)
Hmm, different brand and model. Not the case with GM though, if GM recommends 87 Octane then that is what is fine, using a higher octane doesn't really make a difference with GM vehicles, unless GM specifies that the vehicle should be run on 92 or 93 Octane 87 will do fine.Not the case anymore with all cars. My wives old Pathfinder said right in the manual that regular was recommended, but using a premium fuel will increase performance and is recommended for towing and maximum performance. The 3.6 benefits from multiple ECU timing tables too, not sure about the 4.
Also take in the fact of the switch to winter blended fuels which equates to a little bit of a loss in MPG, winter blends are formulated for the colder temperatures where it's needed and ignites easier during the winter but doesn't have the same Btu's as summer blends.Recent testing has shown that, on the average, cars get about 1.5% to 3% lower mileage with E10 than with regular unleaded. That's about 1mpg if you are getting 30+ in the worst case.
Read the manual, as I said before. Plus I was told this by two techs, as I said.Hmm, different brand and model. Not the case with GM though, if GM recommends 87 Octane then that is what is fine, using a higher octane doesn't really make a difference with GM vehicles, unless GM specifies that the vehicle should be run on 92 or 93 Octane 87 will do fine.
+1. Correct. The 3.6 CAN benefit from higher octane fuel because the ECU/ECM has multiple timing tables, hence the notation in your owners manual about using 89+ octane.Read the manual, as I said before. Plus I was told this by two techs, as I said.
And many of the new GM cars have different timing tables in the ECM. I have used HP Tuners on my other cars and verified it. It is a known fact on LS1Tech and Corvetteforum. The 3.6 has the tables too. We aren't talking about 10 year old Malibus.
Finally someone who #1 read the owners manual and #2 knows something about how modern ECU's can work.+1. Correct. The 3.6 CAN benefit from higher octane fuel because the ECU/ECM has multiple timing tables, hence the notation in your owners manual about using 89+ octane.
The Ecotec 2.4 does not have this ability and will see ZERO benefit from using anything higher than 87 octane... except a lighter wallet.
I have a 4 cyl, A6 2010 LTZ with less than 5000 miles on it. I just pumped some Shell 89 octane in it today. Thought I'd give it a try to see if I can tell any difference in MPG or performance. What do you folks like?
impacted said:The 3.6 CAN benefit from higher octane fuel because the ECU/ECM has multiple timing tables, hence the notation in your owners manual about using 89+ octane.
The Ecotec 2.4 does not have this ability and will see ZERO benefit from using anything higher than 87 octane... except a lighter wallet.See Silver here's where the problem lies, you jump in here without looking at the OP's post. This is why I said that for the OP's it isn't gonna make a difference. By the way all GM vehicles have multiple timing tables. But I've seen where GM does recommend 87 Octane for several cars, some GM even states to only use Premium, I.E. all 3800 Supercharged equipped GM vehicles say to use premium, mainly for the resistance to detonation or pre-ignition which they will experience with regular octane. The only thing about octane ratings is the resistance to detonation in the gasoline engine, tie that into increased cylinder pressures and you can see as the pressure increases inside you need higher octane to resist detonation. Does it mean that anything over 87 is a benefit to the majority of GM vehicles, no not really, you won't see anything noticeable it's just your perceived notion of a change.
If you read all the posts, you would see some of us were talking about the 3.6 too. So stop acting like you know something.See Silver here's where the problem lies, you jump in here without looking at the OP's post. This is why I said that for the OP's it isn't gonna make a difference. By the way all GM vehicles have multiple timing tables. But I've seen where GM does recommend 87 Octane for several cars, some GM even states to only use Premium, I.E. all 3800 Supercharged equipped GM vehicles say to use premium, mainly for the resistance to detonation or pre-ignition which they will experience with regular octane. The only thing about octane ratings is the resistance to detonation in the gasoline engine, tie that into increased cylinder pressures and you can see as the pressure increases inside you need higher octane to resist detonation. Does it mean that anything over 87 is a benefit to the majority of GM vehicles, no not really, you won't see anything noticeable it's just your perceived notion of a change.
The octane level will not affect your fuel filter. Let me repeat. The fuel filter will not affect your fuel filter. Lower octane gasoline is not dirtier or less filtered or any such thing. The 4 cyl. engine is fine to be run on 85. In fact, 90% of people will not notice a difference tfomr 85 to 87 or 91 or even 93, except the cost. If you have a turbo charger, that is different. The 6 cyl. engine may run a little better on 87 +, but 87 is probably fine and the noticed differences are pretty small. The only reason I ever run higher octane fuel is if it is a station tat sells the high octane with no ethanol (in WI the low grades have to have a minimum of 10% ethanol).I'd say the best to use is 91 octane. As the 4cyl is not a high performance vehicle 91 is sufficent. whatever u do though, never run on 87 octane or lower as that will cause problems for your fuel filter and it will misfire, and drive like crap. Thats from my experience
It isn't that octane that can make a filter dirty, it's low quality gas that can.The octane level will not affect your fuel filter. Let me repeat. The fuel filter will not affect your fuel filter. Lower octane gasoline is not dirtier or less filtered or any such thing. The 4 cyl. engine is fine to be run on 85. In fact, 90% of people will not notice a difference tfomr 85 to 87 or 91 or even 93, except the cost. If you have a turbo charger, that is different. The 6 cyl. engine may run a little better on 87 +, but 87 is probably fine and the noticed differences are pretty small. The only reason I ever run higher octane fuel is if it is a station tat sells the high octane with no ethanol (in WI the low grades have to have a minimum of 10% ethanol).
Hmm the same thing I said, as it is most automobiles will run fine on 87 octane and using higher octane won't make a noticeable difference. Using high octane gasoline is better for high performance applications that see a higher internal combustion pressures that can cause hot spots and the possibilty of detonation or pre-ignition, hence the GM recommendations for turbocharged and supercharged engines is to use premium gas.The octane level will not affect your fuel filter. Let me repeat. The fuel filter will not affect your fuel filter. Lower octane gasoline is not dirtier or less filtered or any such thing. The 4 cyl. engine is fine to be run on 85. In fact, 90% of people will not notice a difference tfomr 85 to 87 or 91 or even 93, except the cost. If you have a turbo charger, that is different. The 6 cyl. engine may run a little better on 87 +, but 87 is probably fine and the noticed differences are pretty small. The only reason I ever run higher octane fuel is if it is a station tat sells the high octane with no ethanol (in WI the low grades have to have a minimum of 10% ethanol).
