ballen2000

So what are you feeding you car? basic unleaded, mid grade, or High octane? Do you see a difference?

I use to feed my xB("Toasty") high octane but prices here in LA are to high now. The high octane gave my car great burst of acceleration from a dead stop but the basic 87 octane just won't give me the power.

I did notice that the high octane gave me about 35 mpg and the 87 only gives me 32 mpgs

cyergey

I've never used anything above 87. I have averaged 33.23 MPG over 14,400 miles.

rdclark

Never get less than 30, driving an auto in Philly & environs, using any brand-name regular gas (Sunoco more often than not).

r

swartzautoman

iTrader: (3)

i use regular 87
i get around 34 mpg on average.
i drive a good mix of city & highway.
i use a special home made mix i put in my tank with every fill up. ive tried bouncing back and forth with the mix to doubble check my findings. with out the mix i get around 31 mpg.
so i always use the mix now.

i use: 4oz of 100% pure acetone
3oz of Lucas upper cylinder lubricant

i mix it in a (empty & clean) 20oz soda bottle and fill the rest of the way with gas and mix it all up real good.
i put 1 bottle per full tank.
it idles smoother, better ecceleration, and getter mpg, what more could you ask for.

crashdad

Always around 32 mpg in a mix of city (mostly) and highway (some). Just pump plain ol' 87 octane, although I always buy one of the 'brand' names like Shell or BP.

draxcaliber

sigh...again, octane ratings on gas have nothing to do with performance or fuel efficiency. it doesn't burn quicker or slower or more effectively in anyway that will net you higher mpg.

octane ratings are simply a measure of the gas's detonation resistance.

when fuel and air are compressed, at a certain point they will auto detonate, as in combust on their own. you don't want this to happen, you don't want fuel and air to ignite until your spark plug sets it off.

if you have a high performance high compression engine in a corvette, and you run low octane gas in it, the gas will auto detonate causing pre-ignition (we all know pre-igition is a bad thing right?).

now there are differences between quality gasolines with better detergeants that will prevent carbon build up and deposits in the engine. but that can also be remedied by using some fuel system cleaner every oil change.

SlvrToaster

Your statement is not necessarily true. Higher rated octane is required for high performance, it reduces the risk of knock... You stated that yourself in your post. High compression and boost fed vehicles like the good stuff... it enables them to operate at optimum performance. If there were no benefits from running different octanes then I am sure when we pulled to the pump we would only see one rating across the board.

draxcaliber

it just depends on how the engine is designed to operate.

cadillac escalade makes 403 hp, runs on 87 octane, scion tc, 160 hp, 87 octane, toyota fj cruiser makes 236, it needs 89 if i remember correctly, corvette makes 405, but it needs 91.

knocking is pre-ignition because of the gas detonating too early. if you put 87 octane in your non boosted scion, and it knocks, then you bought some really cheap falsly rated gas.

from wikipedia

SlvrToaster

You can get a bad tank of gas at any station at any time (or all the time at AAFES). My old 04 WRX and the 05 Legacy GT that I still have run 10x better on 93oct. But its hard as hell to get ahold of up here in CO. I think your statements about no performance edge and mpg difference you referred to were just made about the xB.. not all autos in general then right?

draxcaliber

https://www.scionlife.com/forums/vie...929&highlight=

go here and watch these videos.

especially part two around the 5:25 mark.

anyway, is it colorado or some other state in that area that sells lower octane gas like 85 octane because of the weather and altitude?

but my mom has a 2005 legacy 2.5 gt limited, it runs just fine on 91 octane. there are a few stations in md that sell 93 octane, but my mom is pretty regular about where and when she fills up, so it never comes up really.

daneisthegreatest

iTrader: (1)

haha AAFES gas sucks so much...its basically watered down gas...i have only put Chevron gas from the same gas station and same pump (pump 11) since new...i dont know might be the OCD kicking in but its nice to have a routine every saturday night :-)

SuperMario6582

i usually get between 31-33 and i just use the 87. i always get my gas from shell or mobil.

BoxOffice

I average about 34-35 when I'm not paying attention - which is most of the time these days, now that I no longer have that ungodly commute. I've got a 5-speed, run sticky 205-wide tires, and I only use 87 octane (higher octane does you no good in these cars unless you've done the extensive mods to accomodate it).
That said, I've gotten up to 43.86 when really trying.
The WORST I've ever gotten was 30.0, all city driving with the A/C on 100% of the time.

Beats my old T-Bird's 19 mpg!

EasysBox

with the octane rating... throw timing into the mix...

pooder

I get 32-35 mpg using 87 octane from SuperAmerica for my 10-mile commute of mostly 55-mph county roads and a couple miles of 40-mph city streets with traffic lights . . . .

SlvrToaster

Some engines actually do need higher octane fuel, such as race engines with very high compression and some turbocharged engines, such as the import version of the Nissan Skyline. Also, a few vehicles, such as the new BMW K1200R motorbike, can sense knock and adjust their engine tuning to take advantage of higher grade fuels. Another user commented that the 2004 BMW 330 also does this, according to the driver's handbook it makes 231 BHP on 98 octane and 221 BHP on 95. This ability is apparently widespread amongst German performance cars using Bosch / Siemens electronic engine controls.

This is a older article. But applies to a majority of the newer ECU programming that we have in American/European/Japanese cars... I have first hand experience with this. On different turbocharged and high compression motored vehicles. The ecu is constantly making adjustments (to include timing) while you drive. Just like if its a colder day, the air is more dense and your vehicle will benefit from it or ie; run stronger.

Tell you what try this: take your moms car to the track.. run 1/4 tank of 91 in it and then 1/4 tank of 93 (driving a few miles prior to running on the 93) this gives the ecu a chance to recalibrate for the higher octane. Compare your time slips and let me know how they look. And at that point let me know if there is no difference in the times your running. It might not be much... maybe only 1/10th of a second.. but it will run quicker, provided you allowed the ecu time to relearn the higher rated fuel and your driving is consistent.

To say that different octane ratings have no benefit doesnt make sense what so ever. If you feel that they dont... put some 87 in your moms car and go out and beat on it. And see how well it runs afterwards. It will probably sound like someone is hitting the block with a hammer when your finished.. The cel should kick on and put it into limp mode. Hopefully preserving the awesome powerplant that it is.

draxcaliber

i didn't say they don't have any benefits. they are made for a reason, and that is to make engine that run boost and high compression reach their optimal power output. but to put anything higher in a scion engine is a waste of money unless it is boosted, or pistons are changed to run on higher compression.

now, how does the ecu calibrate itself to higher octane gas? it has a knock sensor to detect if the gas is of a lower octane, but how does it know if the new tank of gas you filled up with is a higher octane, does it occasionally adjust the timing at idle or something to determine if it is safe to advance or retard timing?

SlvrToaster

http://www.autoshop101.com/forms/h59.pdf
Here is a bit of insight into it with a actual talk about advanced Toyota ECU's. Its a backwards forwards look at it.
http://www.autoshop101.com/autoshop15.html#OBD2
This link here will pretty much answer any question you could ever have electronically about the Toyota OBD II ecu. ALOT of good data on that page... lots of reading too :D

HMRNBOX

You need to change the polls, I average only about 23-24mpg around town...sh*tty, I know. Now on the way back from AZ I got 38mpg.

EasysBox

23-24?... i think you like your throttle a little too much ;)