# is high octane needed for highway?



## enjracing (Jun 7, 2006)

i spend 95% of my driving on the freeway and was wondering if that really needed high octane gas? i shift at low RPM's and usually am in "gas conservation" mode when driving the goat. it never hear it detonate with the low grade gas, even when i'm on it, but i am wondering if that's because the computer is pulling timing to compensate. will it actually end up hurting my gas mileage overall because of this?


----------



## noz34me (Dec 15, 2005)

enjracing said:


> i spend 95% of my driving on the freeway and was wondering if that really needed high octane gas? i shift at low RPM's and usually am in "gas conservation" mode when driving the goat. it never hear it detonate with the low grade gas, even when i'm on it, but i am wondering if that's because the computer is pulling timing to compensate. will it actually end up hurting my gas mileage overall because of this?


This is a very polarizing subject on most GTO boards, as many feel a high performance engine needs premium gas. 

The truth is, the engine is designed to adjust timing to accommodate down to 87 octane gas. I believe it also states that in your owners manual.


----------



## k1200lt (Jan 18, 2006)

As in the manual:

Gasoline Octane
Use premium unleaded gasoline with a posted octane of 91 or higher for best performance. You may also use middle grade or regular unleaded gasoline rated at 87 octane or higher, but your vehicle's acceleration may be slightly reduced. If the octane is less than 87, you may get a heavy knocking noise when you drive. If this occurs, use a gasoline rated at 87 octane or higher as soon as possible. Otherwise, you might damage your engine.


----------



## CopperD (Apr 22, 2006)

Its only $4 more to run high octane, is it worth it to damage your car to save a few dollars. My main worry is that if you get a tank of bad gas you wont have enough time to stop engine damage. The adjustments it makes to use 87 will also hurt your fuel mileage how much I dont know but it would be a nice test. I would like to know how much it is retarding the timing to run 87 if you have a scan tool around.


----------



## GOGTO007 (May 18, 2006)

CopperD said:


> Its only $4 more to run high octane, is it worth it to damage your car to save a few dollars. My main worry is that if you get a tank of bad gas you wont have enough time to stop engine damage. The adjustments it makes to use 87 will also hurt your fuel mileage how much I dont know but it would be a nice test. I would like to know how much it is retarding the timing to run 87 if you have a scan tool around.


:agree It's only a couple dollars. Your driving a 30K car. Come on.


----------



## MJGTOWISH (Jun 15, 2006)

*Why not an fuel addivitve ????*



enjracing said:


> i spend 95% of my driving on the freeway and was wondering if that really needed high octane gas? i shift at low RPM's and usually am in "gas conservation" mode when driving the goat. it never hear it detonate with the low grade gas, even when i'm on it, but i am wondering if that's because the computer is pulling timing to compensate. will it actually end up hurting my gas mileage overall because of this?



If you are so worried why don't you just use an high octane additve when you fill up that is what i do for only 5 Bucks boost 87 to 100 up to 20 gallons of fuel it is better than for 5.50 for 100 octane and 3.75 for 93octane if you add it up for 87 octane plus the addivte costs 49.85 for 100 octane it is 82.50
for 93 56.25. this is for 15 gallons of fuel I think that is the size for the GTO.


----------



## 05 goatman (Sep 13, 2005)

silly question but i thought if you use higher then 94 oct it would clog your cats on a stock exuast?


----------



## MJGTOWISH (Jun 15, 2006)

05 goatman said:


> silly question but i thought if you use higher then 94 oct it would clog your cats on a stock exuast?



Ther is no difference in sounds or peformace, but 110 would do that.


----------



## enjracing (Jun 7, 2006)

i'm not trying to be cheap, just wanted to know. so, i would say that if enough timing is retarded, it would make you have to use more throttle to accelerate the same amount and have to use more throttle to keep the car moving at highway speeds. therfore, using moe gas than with the premium grade.


----------



## GTO JUDGE (May 14, 2005)

Here is what I do... I posted this before...... I alternate between 89 and 92 octane. One gas up I will do the premium, and the next, I will do the mid grade. I usually gas up at 1/2 tank. This works great for me.... I just got back from a round trip jaunt from Lancaster PA to Near Pittsburgh PA to view the flight 93 memorial and this what I got.....
to Pitt..... on premium...... 27.3 mpg
trip home........ 28.4 mpg on mid grade at the first gallon..... from start to finish at 70mph I pulled in my drive and it was an even 28mpg. 2 hours 34 minutes.

Alternating fill ups this way will help a little in the $$ dept and you will not notice it all.


----------



## kwiktsi (Apr 5, 2006)

MJGTOWISH said:


> Ther is no difference in sounds or peformace, but 110 would do that.


Leaded fuel will do that regardless of octane....
Joe


----------



## kwiktsi (Apr 5, 2006)

MJGTOWISH said:


> If you are so worried why don't you just use an high octane additve when you fill up that is what i do for only 5 Bucks boost 87 to 100 up to 20 gallons of fuel it is better than for 5.50 for 100 octane and 3.75 for 93octane if you add it up for 87 octane plus the addivte costs 49.85 for 100 octane it is 82.50
> for 93 56.25. this is for 15 gallons of fuel I think that is the size for the GTO.



Read the octane boosters carefully- they do not give you nearly that much. From speaking with an STP rep one time, it is a different "points" system thanwhat the octane is rated at. If they say they give you 5 points, it does not make 94 99 octane, it makes it 94.5. At least that's how the rep described it to us. Over the counter octane boosters are usually a waste of money.
Joe


----------



## GOGTO007 (May 18, 2006)

kwiktsi said:


> Read the octane boosters carefully- they do not give you nearly that much. From speaking with an STP rep one time, it is a different "points" system thanwhat the octane is rated at. If they say they give you 5 points, it does not make 94 99 octane, it makes it 94.5. At least that's how the rep described it to us. Over the counter octane boosters are usually a waste of money.
> Joe


:agree +1
That is a way off base way to get more octane. Those additives don't do crap. They are nothing like getting high octane gas from the drag strip. You could probably add 10 of those STP bottles to your tank and gain maybe 1 octane point.


----------



## MJGTOWISH (Jun 15, 2006)

I used 93 before gas was 2.50 gal when I used the booster you could really fell the changed in accelartion of the car ,it was better than any 93 octane gas I have used (it was a booster for 100 ocatne) to test any liquids (gas,oil) I test it in my lawn mower I known it sounds funny but it is good to test something you are not sure about rather than risking you 30k car engine!!!!! and it seemed to run better let just say I cut my half acre back yard in about 15 mins give or take.


I did not use stp I used somthing in a red and green bottle it was relly werid name i can not rember when i buy some i will let you know!!!!!


----------



## GOGTO007 (May 18, 2006)

All I'm saying is that it might make your car run a little better, but it is not raising your octane by much at all. Anybody that knows anything about fuel and octane rating will tell you the same.
If they were that affective you'd see professionals using little bottles of additive at the drag strip in their drag cars.:rofl:


----------



## Clueless (Mar 2, 2006)

:agree That's the way I've always heard it, that octane boosters are rated such that 1 (octane boost point) == 0.1 gas rating point.

Also, I don't know much about the mechanics and such, but similar to what some others above have said, I've always heard that using too low an octane gas can cause damage in older engines; in newer engines the car will usually adjust but you will generally get worse fuel mileage, so you are not saving much if any money in the end. And of course, too low and it pings and stuff. On the other hand, I've heard that using a higher octane gas (note that this is assuming the car is stock, not talking modded) doesn't do anything for the car, with the possible exception of if the higher octane gas has more detergents in it. So if the family cruiser is rated for regular, you aren't going to get better performance or anything by running premium.

Anyway, after hearing stuff like the above constantly, I just stick with what the manufacturer recommends for a car. I figure this is safest. I always fill my GTO with premium, same as I did for my Z28 before. Though if I was out on a trip, was in the boonies, and the only gas station around did not sell premium, at least I could fill up on midgrade to get me by.


----------

