gasoline grade

[WintR]

Don't forget, stock, without a tune, you have a ping detector, and the computer pulls the timing back to stop it (the timing isn't that advanced, to begin with). In the 2.4, you should only get pings when near WOT on a very hot day, when using 87.

[dmunst]

Thanks for the info guys. Interesting information about the 89 sitting too long at the station. I have been averaging 21 mpg and drive about 50-60 miles per day for work. In the morning it is mostly highway miles and after work i take side streets (stop and go) to avoid traffic on my way back to Chicago.

[rmahoney]

GXP with Trifecta budget tune. I get almost 20 mpg city with 93.

Bob

[rmahoney]

Originally Posted by CONNER98 89 is a slow seller at most stations,and sits longer in the tanks.Ask your station how much 89 they sale on a monthly basis.You may be getting older gas with 89.

I thought that there is really no such thing as 89. The storage tanks contain 87 and 93 and the pump mixes them to create 89. Or is it done at the delivery truck level, it mixes the two as it fills the 89 storage tank....

Bob

[TomShadow]

I have an '07 gxp and (as recommended) have almost always put in premium, however with the large price spread between midgrade and premium of late (30-cents) it is very tempting to bump down a grade. PAid 3.859/gallon the other day; regular was 3.359 (not sure what midgrade was that day).
I've used midgrade a handful of times when I was really short on cash or the station was out of premium, but for the most part I put the good stuff in.

[Rusty Boltz]

I don't put a lot of miles on my 2.4, so I spend the few extra cents for premium.

[CONNER98]

Originally Posted by rmahoney I thought that there is really no such thing as 89. The storage tanks contain 87 and 93 and the pump mixes them to create 89. Or is it done at the delivery truck level, it mixes the two as it fills the 89 storage tank.... Bob

The 89 comes from the loading rack the same as diesel,87,93,jet fuel.I was told gas companies were trying to phase the 89 out,but that was just rumor.
The driver,nor store does any mixing here.
If you look at the drop slots at each service station you should see color coded lids.Red-premium,Orange-diesel,Blue-mid grade,White-vapor recovery,or where you stick the tanks for levels.I may have missed some of those colors,but you get the picture
The tanker trucks normally have 5 compartments.The biggest compartment is usually 2500 gallons,and smallest around 900-1000.
The newer stores tank levels are monitored online.Once levels get to a certain percent an order is sent out to the driver.Stores like to keep levels at an 80% full level.Its up to the driver to make sure the tanks will hold it.Theres nothing worse than a overfill/spill.
Anywhoo Im rambling.I didnt do it for a long time,but it was interesting while it lasted.It wasnt fun trying to make a living driving around with a 10,000 gallon bomb on your back trying to make 5 stores a day

[CONNER98]

Originally Posted by rmahoney I thought that there is really no such thing as 89. The storage tanks contain 87 and 93 and the pump mixes them to create 89. Or is it done at the delivery truck level, it mixes the two as it fills the 89 storage tank.... Bob

Sorry Bob I stand corrected!
The station below my house does in fact mix his 89.
I had no idea on that one.My local station gets one load a week,where I was use to stores that got 2 trucks in a 24 hr period.He says he still sells plenty of 89.
The big city folk I guess buy more 87,and 93?

[JRinKY]

I did a series of tests switching between all three grades of fuel. I ran a minimum of two tankfuls of each, and tried to keep my driving as consistent as possible throughout the tests. I checked fuel economy by the DIC and by calculator (they consistently agree to within 1 MPG), and did performance tests using a G-Tech Pro and my favorite mile-long stretch of straight, level back road. The tests were absolutely consistent going up and down in octane. Twice.

The first tankful of different-octane fuel yielded better mileage. Up or down in octane, it didn't matter. The second tankful reverted to the same economy I usually get.

The G-Tech measured the same peak power for all octane levels.

All of the tests were done using Shell fuels, mostly from the same pump at the same station to keep the fill-ups consistent.

[MyBlueCar]

The consumer magazines say go for the lowest grade of gas that doesn't cause your car to ping. I've been using 87, without problem...

[TomatoSoup]

Originally Posted by MyBlueCar The consumer magazines say go for the lowest grade of gas that doesn't cause your car to ping. I've been using 87, without problem...

Agggh! That may have been true for older cars, but in modern cars with computer controls and knock sensors you cannot hear 'ping' (or if you can, it's probably too late and you've damaged your engine). Do NOT follow that advice.

In any case, I think the actual recommendation is "use the lowest grade of gas that is recommended in your owners manual"

[JRinKY]

TomatoSoup: Agggh! That may have been true for older cars, but in modern cars with computer controls and knock sensors you cannot hear 'ping' (or if you can, it's probably too late and you've damaged your engine). Do NOT follow that advice. In any case, I think the actual recommendation is "use the lowest grade of gas that is recommended in your owners manual"

Or you can confirm that the knock sensor is not commanding spark retard and feel confident that 87 octane is not causing a problem.

I will admit to only having done about 90k miles of testing so far, but everything still looks pretty good.

[KellyfromVA]

As JRInKy mentioned, I've seen similar results. As a test this past few weeks, I ran one tank (to 1/8 tank) of each grade on the same 80 mile round trip commute. Surprisingly, 93 and 89 octane showed no change in fuel economy nor degradation in overall performance. Ironically, 87 octane fuel yielded 1 MPG additional fuel economy over 89 and 93. The test used fuel(s) from the same gas station. My former 2009 Lexus IS used to have a fairly significant difference in fuel economy between 89 and 93 octane fue;, about 4 MPG difference. So, what have we learned here? Its true what they say in the disclaimer; results may vary.

[JRinKY]

Theoretically, and assuming no knock retard to decrease engine performance, 87 octane fuel should yield better performance, as it contains more energy per unit volume.

[rob the elder]

Consider reading this thread about connecting rods.

Factory LE5 Connecting Rods - PLEASE READ

Knock is bad. But for some hardware configurations its really really bad.

And we have more than a few examples of 2.0 cars knocking audibly when running "normally". As in long periods of cruise followed by a burst of high throttle will result in audible ping in most 2.0 cars.