Truth about running higher octane than require

[ionbeam22]

If its a modern car with automatic timing, and knock sensor (e.g pretty much all cars in the past 10+ years) then a higher octane may lead to adaptive timing of the ignition to give more power/milage.

Otherwise the premium gas will usually have more additives in it, and may have less ethanol in it. The mid grades are usually just various blends of 93 and 87.

IMHO if you want additives, you'll do better to pour some in yourself. You can get a quart of Lucas UCL for $10 at autozone, and that should be enough to last you over 10 fillups.

You could get Regane for like $6 at autozone, and it would cost the same as spread between 87 and 93, if you used it every other tank. It would probably have more cleaning power than two tanks of premium would.

 

[lexus114]

Originally Posted By: SevenBizzos
My Hyundai runs more efficient on 89 than 87 by 1-1.2mpg. My crackhead dealer service manager gave me the idea saying that 2.0L engine runs better on premium. I didn't believe him but went half-way to see if there was a difference. I've been at it for 60k miles and it does make a difference. The owner's manual uses the "87 octane or higher" terminology as well.



so does my daughters 02 Elantra.

 

[StevieC]

Not all cars have Knock sensors. My '06 Santa Fe doesn't and my mom's Kia also doesn't.

As for the 4 Cylinder Hyundai/Kia engines, they do seem to run better and get better mileage on the '89 Octane as my moms does and that is what she runs. (Enough to negate the cost difference)

 

[mechtech2]

Knock sensors are just little microphones.
Kinda crude.
And they go off in many cars for no good reason. They pick up all sorts of vibrations and noise that is not spark knock.
I disconnected mine and enjoyed a smoother powerband, as do others.
But I use at least mid grade fuel.
Not all cars benefit from unplugging the KS, but many do.

 

[lexus114]

Originally Posted By: mechtech2
Knock sensors are just little microphones.
Kinda crude.
And they go off in many cars for no good reason. They pick up all sorts of vibrations and noise that is not spark knock.
I disconnected mine and enjoyed a smoother powerband, as do others.
But I use at least mid grade fuel.
Not all cars benefit from unplugging the KS, but many do.



Doesn that throw your check engine light on??

 

[d00df00d]

Originally Posted By: lexus114
Doesn that throw your check engine light on??

It didn't on my old Maxima ('95).

It did, however, make the car pretty sluggish...

 

[lexus114]

Originally Posted By: d00df00d
Originally Posted By: lexus114
Doesn that throw your check engine light on??

It didn't on my old Maxima ('95).

It did, however, make the car pretty sluggish...


Oh a pre OBDII thats probably how you got away with it.The OBDII system is very intense.

 

[StevieC]

Not intense, Anal is more like it.

"Oh, you closed the door too hard, lets turn on the CEL!" Oh wait, that's GM...

 

[severach]

With gas additives found here on BITOG I reduce engine noise levels back to factory levels. In addition to a much more pleasant engine sound the knock sensor no longer hears the din as knocks.

 

[crinkles]

I use this E10 - RON 95

http://www.unitedpetroleum.com.au/index.asp?pgID=66

cheapest fuel, and gives me more octane. my camry runs noticeably better on RON95 than 91...

 

[Ken2]

Chevron says:
Quote:
Using gasoline with an antiknock rating higher than that required to prevent knock or to
prevent spark retardation by the knock sensor will not improve a vehicle’s performance.

http://www.chevron.com/products/ourfuels/prodserv/fuels/documents/69083_MotorGas_Tech Review.pdf, Page 7

A few years ago "Car & Driver" magazine tested several different cars on a dynamometer with different octane level gasolines. Their findings were that using regular in an engine designed for high octane resulted in slightly less power and slightly extra gas usage so the total fuel cost per mile was equal. Using high octane in an engine designed for low octane gas resulted in power readings on the dyno that were insignificantly different within the range of error of the dyno's instruments.

I have never seen any qualified reports of high octane gas in a low octane engine resulting in any engine damage of any sort. Wallet damage, yes.

 

[ekpolk]

And then there are cars like this:

This is from the manual from the 2003.5 V-6 Camry I used to drive. Apparently, the engine was designed to respond to all fuels well. A year or so later, as I understand it, the gov't came down on car makers who were advertising HP and TQ figures based upon the use of premium fuel, and made them start advertising the figures for the engine when fed the lowest acceptable octane fuel. This engine "lost" about 20 hp when the requirements changed, dropping from the 210 hp when I bought mine to 190 the next model year... Yes, in engines designed to deal with different fuels, octane certainly does make a difference. BTW, FWIW, I never ran regular in mine!

 

[Nederlander75]

You may get more carbon, but a good add pack would cover you there. When using WAY more octane there are start up issues and power loss, from my experience.

 

[ekpolk]

Originally Posted By: Nederlander75
. . . When using WAY more octane there are start up issues and power loss, from my experience.


A valid point. The Prius O/M cautions against using premium. Since the car goes through so many starts, it needs to fire up right away, with no hesitation.

 

[CharBaby]

My Lexus RX-300 OM says the same thing... "87 is fine, and higher octane for improved vehicle performance".

 

[LTVibe]

Originally Posted By: ekpolk
This engine "lost" about 20 hp when the requirements changed, dropping from the 210 hp when I bought mine to 190 the next model year... Yes, in engines designed to deal with different fuels, octane certainly does make a difference. BTW, FWIW, I never ran regular in mine!

This is an old article (2002), but the fuel issue was similar for the Accord:

http://www.usatoday.com/money/autos/reviews/2002-08-01-accord_x.htm

"The Accord V-6 ratings assume regular-grade fuel, and Honda will market it as a regular-fuel engine. But — pssst — it's good for another 10 hp and 10-plus lbs.-ft. on premium, acknowledges V-6 engineer Asaki."

 

[GMBoy]

Originally Posted By: StevieC
Not intense, Anal is more like it.

"Oh, you closed the door too hard, lets turn on the CEL!" Oh wait, that's GM...

Wow you really can't restrain yourself can ya Stevie?

..love the anal part, though, coming from you that is...

(been a long time since I picked on ya!

)

 

[mechtech2]

No engine code can occur from yanking the knock sensor. It doesn't know. 2003 Ford.
There may be some cars that require it to be operational for no codes to be thrown. I don't know about every vehicle.
Honda guys started doing this and many other cars can benefit from elimination of the KS. I have seat of the pants evidence and a bunch of dynos from other cars. They go off and the computer yanks a lot of timing. A wavy powerband results.
I'd rather use the proper octane and enjoy better performance.

 

[lexus114]

Originally Posted By: Char Baby
My Lexus RX-300 OM says the same thing... "87 is fine, and higher octane for improved vehicle performance".


I can most definitely tell the difference between reg.and prem.in my RX.

 

[lexus114]

Originally Posted By: mechtech2
No engine code can occur from yanking the knock sensor. It doesn't know. 2003 Ford.
There may be some cars that require it to be operational for no codes to be thrown. I don't know about every vehicle.
Honda guys started doing this and many other cars can benefit from elimination of the KS. I have seat of the pants evidence and a bunch of dynos from other cars. They go off and the computer yanks a lot of timing. A wavy powerband results.
I'd rather use the proper octane and enjoy better performance.


Yeah and the 1MZ-FE has two knock sensors,and they are a total pita to get to.