PLEASE READ: OCTANE question for '04 GTS

[Celcier]

OK, so I've been doing a lot of reading on different forums about what Octane the GTS takes. there seems to be mixed information about it. I got my '04 Celica about a month ago, and the first tank I filled with Premium. After that, I looked in the INSTRUCTION MANUAL and it said that the car takes 87 Octane, so from then on I only put Regular in it. Now, with the regular, I find that I actually get BETTER gas mileage and it's a far smoother ride (less jerking) than when I use Premium. THat first tank, I got roughly 20mpg. With regular (and I'm not lying about this) I get between 28 and 35mpg (it's a manual and I ride in Neutral when I'm not giving it gas). Can someone please tell me why the manual says to use Regular and everyone else says to use premium? Also, why (unless it was driver error) did I get better gas mileage and a softer ride with the regular gas? I don't experience ANY knocking, but I do experience less Zip then with premium, but that doesn't bother me. I do race my car a little here and there and take the Tack up to 7k (but not often at all, just for fun)...so will the regular gas hurt my car? Thanks for your help.

[cwk]

first off are you sure you hace a GTS? im asking this because you said you only rev it up to 7k where in a gts you would generally shift around 8k rpm in a race situation. does your tack redline at around 8k? and in the manual it gives info for both the GTS and the GT. it says the GT takes 87 octaine(regular) and the GTS takes 91 or higer(premium) if you do have a 2zz gts you should run at least 91 octaine at all times if you care about your car. the high compression of the 2zz does not like cheap gas.

[Celcier]

QUOTE (ckw @ Jul 16 2008, 12:00 PM)

first off are you sure you hace a GTS? im asking this because you said you only rev it up to 7k where in a gts you would generally shift around 8k rpm in a race situation. does your tack redline at around 8k? and in the manual it gives info for both the GTS and the GT. it says the GT takes 87 octaine(regular) and the GTS takes 91 or higer(premium) if you do have a 2zz gts you should run at least 91 octaine at all times if you care about your car. the high compression of the 2zz does not like cheap gas.[/B]

It is a GTS. I only rev the Engine to 7k cuz hearing it whine at 8k scares me, and since I'm only revving it that high for kicks by myself (I'm not racing against anyone) I don't take it too high. MY car is currently in the shop getting new brakes, so I'll check the manual a third time and confirm your comment. The next tank I'll fill with Premium and see how it runs, now that I've run it with regular for a month, I can really compare. This weekend I'm driving down to North Carolina (7 hour trip each way) so I'll get a lot of opportunity to test it. I'll repost my studies and results here Sunday night. Thanks for your help, buddy!

[Kastigir]

If you use a higher octane than required by your car, you will get less mileage.

[Celcier]

ok, so here's the follow up:

I put 93 Octane in the car of the entire trip. I noticed a SLIGHT upgrade in gasmilage (maybe 1-2miles per gallon making my average roughly 34mpg) as well as a significant increase in boost over the 87 Octane. The jerkiness that i was experiencing from the First tank of Premium gas was simly driver error, i didn't really know how to drive it just yet cuz it was a new car. With the 93, it drove JUST fine. Thanks for humoring me with responses everyone. Take care.

[cwk]

QUOTE (Celcier @ Jul 28 2008, 02:04 PM)

ok, so here's the follow up:

I put 93 Octane in the car of the entire trip. I noticed a SLIGHT upgrade in gasmilage (maybe 1-2miles per gallon making my average roughly 34mpg) as well as a significant increase in boost over the 87 Octane. The jerkiness that i was experiencing from the First tank of Premium gas was simly driver error, i didn't really know how to drive it just yet cuz it was a new car. With the 93, it drove JUST fine. Thanks for humoring me with responses everyone. Take care.[/B]

good to hear.. you gonna be running 93 from now on?

[Col]

QUOTE (Kastigir @ Jul 17 2008, 07:45 PM)

If you use a higher octane than required by your car, you will get less mileage.[/B]

Why is that?

[MA70Supra88]

QUOTE (Col @ Jul 28 2008, 11:00 PM)

QUOTE (Kastigir @ Jul 17 2008, 07:45 PM)

If you use a higher octane than required by your car, you will get less mileage.[/B]

Why is that?
[/B][/QUOTE]
Higher octane fuel burns at higher temperatures. An engine with a lower compression designed to burn 87 doesnt burn the 91 octane gasoline as efficiently, resulting in a loss of power and mileage. Higher octane fuel is only needed to prevent detonation that would occur in a high compression engine on lower octane fuel.

[Col]

QUOTE (MA70Supra88 @ Jul 29 2008, 09:47 AM)

QUOTE (Col @ Jul 28 2008, 11:00 PM)

QUOTE (Kastigir @ Jul 17 2008, 07:45 PM)

If you use a higher octane than required by your car, you will get less mileage.[/B]

Why is that?
[/B][/QUOTE]
Higher octane fuel burns at higher temperatures. An engine with a lower compression designed to burn 87 doesnt burn the 91 octane gasoline as efficiently, resulting in a loss of power and mileage. Higher octane fuel is only needed to prevent detonation that would occur in a high compression engine on lower octane fuel.
[/B][/QUOTE]
Thanks for the info.

[tracerxzero]

if the car isnt missing any of the labels you could of just opened the gas door and saw that nice little black sticker on the inside of it that says "premium unleaded only" and saved yourself a ton of typing