unleaded or plus

[falkor_99]

I know the yaris runs fine on unleaded but my friend who graduated from UTI always puts plus in his car just to make the gas last longer. So I tried this the last time i filled up to see if the my gas will last longer.

So if anyone has already tried this or has any input, that would be awesome.

[brickhardmeat]

REG UN for me

[squibby]

I ran my yaris l/b on regular for about 4 tanks and got around 34-36mpg each time. Tried plus on the fifth tank and got around 32mpg. I didn't try another tank of plus so I can't be sure if it was the gas or my driving style. But yeh, I only fill with regular now.

[falkor_99]

hmmmmm, very interesting. Thanks for the info.

[brickhardmeat]

there is a more indepth thread posted on this a while back, lots more opinions

[tekmoe]

i run regular.

[churp]

I run the plus (89octane) it's usually only 2 cents above reg here in MN, and all gas has alcohol in the state. Consider if plus was 3 cents higher than reg at $3.00/g that's only 1% increase.....if you were getting 35 mpg on reg then a 1% increase would be 35.3 mpg to give a payback. I got 32 to 35 mpg the 1st 4,300 miles....then I put more air in the tires,went to plus, and put my lowering springs on.....since then I have gotten from 37 to 42 mpg (39 mpg avg since 4,300 m) and have 9,000 miles on the car. Did the plus do it???? Hell if I know, but I'm not going back to reg!!!!

[uncleyaris]

IMO if our cars needed it, Toyota would have us use it. Don't waste your money.

[swng]

I am doing fine with regular. I have tried Octane No. 92 but have found no proof that the car benefited.

[BailOut]

Remember that Octane is not a measurement of caloric value (that would be Cetane) but of heat resistance. All higher Octane fuel does is require a hotter temperature to ignite, which can cause your timing to advance a bit.

Granted, I'm a hypermiler, but if I can pull 52 MPG on 87 Octane then there's absolutely no need for anything higher unless you are having problems with knock (detonation), in which case I'd have my Yaris into the shop long before I changed fuels anyway.

[churp]

Does a hypermiler ever push the thottle down enough where the ecu could take advantage of higher octane? I can see where higher octane would never help in that situation, and I agreeunder those conditions. But in a 10.5 compression ratio car detonation does occur if timing is not retarded under load....thus I fully believe it does help under the normal everyday driving like most people do. I do pass people, I do drive 70 to 80 including up hill, and I do believe it helps by more than the fraction of a percentage that it costs me. Theoretically higher octane helps when the engine is used to its maximum, and theoretically it would be no help if you drive like you have an egg between your foot and the gas pedal...believe what you will, but without the ecu and the knock senser you would either have to drive like a hyper or your engine would self destruct or you would have to retard the timing which would reduce even the hypers milage.

The ecu and sensors adapt so you can use 87 octane, but higher octane helps achieve better milage when under heavy load. I sometimes wonder if there are any hypers out there old enough to have ever driven non computerized cars...they were all timed to just approach detonation under load according to the gas you used, which gave best performance (power and gas millage).

Gettin to old and windy....in short, hypers never need 89 the ecu protects them on rare occasions, lead foots could possibly notice better power and better milage.....so everybody do what they want, we're all adults.

[Kaotic Lazagna]

i run regular. but the time that i did run premium, not plus, i got a mile or two more per gallon.

[BailOut]

As churp mentions I suppose a 2 MPG boost might aid someone that drives aggressively but it wouldn't be worth it for me.

I've been paying $3.40/gallon lately, so $3.40 / 50 MPG = $0.068 per mile

Premium in my area costs about $0.20 higher than regular. If I were to get a 2 MPG boost from the premium fuel I'd actually be spending an additional $0.064 per gallon for no appreciable gain.

[swng]

I know that higher octane fuel can help prevent knocking for cars with a relatively high compression ratio. Higher octane can prevent early ignition when compression gets high (this is hardly technical language). However, there are views that say when high octane fuel is not needed by your car, then there is no need to buy it:
http://www.ftc.gov/bcp/conline/pubs/autos/octane.shtm
http://www.wisegeek.com/what-is-high-octane-fuel.htm
I personally have an open mind on this anyway.

[churp]

Originally Posted by BailOut

As churp mentions I suppose a 2 MPG boost might aid someone that drives aggressively but it wouldn't be worth it for me.

I've been paying $3.40/gallon lately, so $3.40 / 50 MPG = $0.068 per mile

Premium in my area costs about $0.20 higher than regular. If I were to get a 2 MPG boost from the premium fuel I'd actually be spending an additional $0.064 per gallon for no appreciable gain.

I applaud your milage BailOut, and agree that your driving technics would not benefit from anything above 87 octane. I look at these threads on milage as a discussion of opinions, because proving any benefits in the real world would almost be impossible....you're proving your point just by your records! I doubt a 2 mpg improvement can actually be gained just because of octane, but feel the 2 cents I pay extra for the plus 89 octane (under 7 tenths of a percent extra) gives me more than the .3 mpg for payback (1.007 X 39 mpg = 39.273 mpg) plus maybe a little more pickup. I'm maybe a little too oldschool and hard headed, but apreciate viewing everyones opinions....we learn from each other, and all hopefully improve.