thanks
cosmo93940

 

It'll run on whatever you put in it. I use 87 and have no problems.

 

Let the owner's manual be your friend.

 

we do not need anything special. (read the cheap stuff)

 

The book says 87 but if you run midgrade you will get slightly better fuel mileage. I'm surprised with 10 to 1 compression ratio that it doesn't call for a higher octane. :?

 

Just use 87. Mid grade won't change your fuel economy.

 

neither will super

 

actually super may make it run worse.......

 

Some vehicle are so inefficient it doesn't matter BUT I have noticed better mileage with a higher octane. FACT!!! And with a high compression ratio it will run better with premium, but you don't have to use it unless you want to so sometime the premium has extra cleaning agents in it so you don't have to use an injector cleaner.

 

ALL modern fuels have the additives you're talking about. I have noticed NO improvement by running Mid grade, and I have noticed a negligable DROP in mileage by running super. Also, not all High compression engines will run better on High test (91 in CA, 92 or 93 elsewhere). I NEVER use "injector cleaner"; it's snake oil. But if you do store your car, you SHOULD use High test in conjuction with a stabilizer. that is the only time high test will see my tank.

 

If you use injector cleaner on a regular basis it keeps the injector buildup to a minimum. Used it regularly on a Ford van and after 500,000 miles never had to have the injectors profesionally cleaned, so I know it does something

 

Let's say that's true, but do you get enough extra mileage to make up for the higher cost of the fuel?

 

In theory you should get better mileage using a higher octane because the engine will produce more power. More power produced means less fuel needed to obtain and maintain the same speed. However, in my experience the difference is negligible and usually isn't worth the extra money.

Regular: 10Gal X $1.70 perGal = $17.00 10Gal X 34MPG = 340Miles
High Octane: 10Gal X $1.90 perGal = $19.00 10Gal X 35MPG = 350Miles

If the car actually managed to get 1 more mile per gallon you can see the difference is only 10 more miles for a price difference of $2.00. It doesn't make enough difference to justify the money unless the change is much more significant and I've never seen it or heard it.

 

actually the computer retards your timing a bit when you run super so your car will actually run worse and usually get worse mileage...try it run a week on super then a week on regular

 

Wrong wrong wrong. You don't understand octane.

High performance engines require higher octane to compensate for higher compression and more radical valve and spark timing. Higher compression engines generate more heat (pressure = heat, that's basic physics). That heat, along with spark timing that's set a hair sooner than on moderate performance engines, can cause the fuel/air mixture to detonate too soon -- predetonation. This can cause engine damage since the piston is still trying to move up while the burning/expanding fuel is trying to push it down. To prevent this, octane ratings are increased so the fuel can withstand more heat and pressure before igniting. In other words, high octane gas is HARDER TO BURN. It's a cure for a problem, not a magic power juice.

Now, even though the compression ration on the xB/xA/Echo engine is on the high side, its computer automatically adjusts spark and valve timing to prevent predetonation. I suppose you could argue that with higher octane gas there's less likelihood of predetonation, so the computer could back off the timing less, keeping the engine closer to its optimal power band. But then you're left with the cost/benefit question. Using your numbers, $1.70/gallon gas at 34 MPG = 5 cents per mile. Meanwhile, $1.90/gallon gas at 35 MPG = 5.4 cents per mile.

 

$1.70 per gallon? where are you seeing gas for that cheap!? Or are you just using that as a figure? lol.. It's still like $2.09 for regular here in S.FL.

 

Gas is about $1.70 per gallon here in northern SC.

 

Old Punk,
I never said higher octane fuel was "magic power juice". Just as you said, a car using a higher octane fuel will not back the timing down as much. More timing means more power. Hence the over-simplified comment "In theory" the car will make more power when using higher octane fuel.

 

1.84 for reg.
2.07 for super

if there was only a .10 cent diff (or one dollar more per tank)between reg and super i would run super all the time.
by me the diff is about .25 cents per gal. (or 2.50 more per tank)

 

Oh man where you guys are at its pretty cheap for gas....over here in L.A. its $2.41....In my box i always put 89....but im starting to think about putting the cheap stuff...LOL...