Octane and Mileage
 

I was reading around and I have heard mix reviews about this
My 2002 solara is recommended 89 octane its the 1mz engine
I have been running it 87 and averaging 420km a tank about 65 litres
thats about 15L/ 100 km

people who run 89 or 91 say they are getting 11L/100 km

Will I notice any gain if I switch to 89 or 91?

Run the fuel spec'd for the engine.

your ecu is advanced enough to adjust timing due to octane level of the gas.

you will notice performance and yes, gas milage as well going to a lower octane. will it hurt the car? probably not.

You should use the recommended octane from the manufacturer.

Assuming that your car is in tip top condition, you should be able to achieve those numbers. Don't forget, if you change your tire/wheel size, it will yield different results.

I noticed that my fuel for this tank has went by faster than last time.
Usually i filled up with premium in BC, til i discovered pt.roberts, and now it seems that I've lost some efficiency. I swear I was driving slow and shifting low as well.

People think higher octane gasoline somehow has more energy and will create more power/better mileage. This is not true. Octane is a measure of the fuel's resistance to detonation, not how much energy is in the fuel.

Higher octane fuels actually typically have less energy than lower octane fuels. The reason why a high-performance engine can get more power with a high-octane fuel is because you can run a higher compression ratio and more aggressive ignition timing. The gains from a higher CR ratio and ignition are greater than the slight loss from using a fuel with less energy and the net gain is an increase in power.

Spending money on higher octane gas than what your engine is designed for is a waste of money and will actually lower your mielage (although it might be so slight you wouldn't be able to measure it). Add in the increased cost of high octane fuel and you're throwing a lot of money away.

Car recommendation in the manual says 89
Ive been using 87

^ yes you've established that, just follow the manual =.=

:rukidding: Good post but totally out of context for the thread.

OP is using LOWER octane fuel than recommended.

Yes it could impact your fuel economy quite significantly if using lower octane than recommended.

If your car is recommended 87, once awhile treat it 89? or 91? will the engine benefit it?

I only fill up at 1) Chev, 2) Shell, and 3) Esso, perhaps Petro(Last To Consider)

^
Nope.

Stick with 87.

You'd just mess with the timing, your car runs best on 87. Spend that extra money on better engine oil if you want to benefit it.

I go point roberts to fill up gas, only 30 minute drive, and their 89 91 almost same as 87, not too big of difference

Gas almost empty will try it out and report back!

There's no reason that lower octane fuel would reduce your mileage. Under normal driving conditions your engine will only be producing a fraction of its maximum output, so you're not going to run into conditions that require higher octane (like knock from advanced timing or heavy load).

Your engine would definitely produce less power at full throttle (or heavy throttle) but should still perform similarly under light throttle.

I doubt anyone could even accurately measure the difference in mileage between going up or down in octane from the recommended fuel your vehicle takes.

Any math wiz want to calculate the break even point?

So should everybody just fill up on 87?

funny no one's asked if his o2 sensor is pooped, or when the last time he did a tune up was

Wouldn't he have a CEL pop up?

Car is well maintained and has never turned on CEL

that is why I am shocked the car takes so much gas even when I drive it like a granny

doesn't always throw a cel, mileage can suffer as the o2 is slowly dying, in some cases it will others it won't.

maybe ur tires aren't properly inflated, alignment, short trips, its cold out
lots of factors

11km/100 sounds like highway mileage not city mileage for a v6 at least to me

I have a habit of recording km / tank and it always averages 420 regardless of weather for the past 2 years. Except for long trips to whistler etc I get extra 100-150km

Tires are new and I check them every month.

Just filled it up today $90 for 60L vs $82

No just put in what ever the manufacturer recommends and don't waste your money on 94 oct from Chevron or Petro Canada.

i switched to shell.

91/92 octane w/ no ethanol mix.

since "regular" is mixed with a higher percentage of additives compared to the other levels of fuel, should that be a consideration to the octane level of fuel you put in? does 86 become an 85 because of the 10% (or whatever it is) mixture of ethanol/etc that they put in?