: What octane do you use?



dugansz
01-02-04, 04:22 PM
Just wondering what octane fuel to put in my 96 sts. It runs fine on the 87, but read in the manual to use premium(92). Think the higher octane might eventually hurt the aluminum northstar internallly? thanks, jim

AKPsiMC03
01-02-04, 04:39 PM
use 93, it will perform better and your gas milage will go up.

gothicaleigh
01-02-04, 04:41 PM
You should use the 92. If the manual requests it, it most likely will run much smoother on the higher octane. A higher octane will not harm your engine. Many premium fuels contain chemicals that help it burn cleaner too.

You will most likely get a slight(honestly, for the most part unnoticeable) horsepower boost and better gas mileage. If your engine is built for the higher octane there will be a noticeable change in smoothness.

Vesicant
01-02-04, 05:54 PM
Yep you have to run high octane, Northstars were practically created to run only on it... although you can now use 87 as standard on the newer designs... it even says that you will get better results with higher octane (the one it reccomends). Plus , Higher octane will help it run longer because it doesnt create as much carbon build up like a lower octane 87 does.


Never the less, if im correct all cadillacs reccomend high octane just because it improves engine reliabillity and plus gives you more power throughout! :coolgleam

gothicaleigh
01-02-04, 05:59 PM
The new 3.6L LY7 CTS engines actually recommend 87.
But like I always state, if you have the money for the car, you should have the money for the premium fluids.

kcnewell
01-02-04, 06:51 PM
The new 3.6L LY7 CTS engines actually recommend 87.
But like I always state, if you have the money for the car, you should have the money for the premium fluids.


The only flaw in that logic is that if the engine is designed to run on 87 that's what you should run in it. Premium fuels will do you no good and will just cost you more.The octane rating of the fuel is just it's measured ability to resist detonation. It is not something that increases performance on it's own. If the particular engine in question is designed to operate on 93 octane fuel then increasing the octane rating above 93 will have no effect. If the fuel you are using is 87 octane but the engine is designed to run on 93 and you switch to 93 the performance would increase in this example because the engine spark knock control system would detect detonation with the 87 octane fuel and retard the spark from the optimum value to prevent damage...thus hurting the power. Once the spark reaches the optimum value with the 93 octane fuel...no more performance to be gained. In any case, the octane rating of the fuel only needs to be high enough to meet the requirements for that engine. Adding octane beyond that will not help performance. I hope this clears it up for you.

Sinister Angel
01-02-04, 08:39 PM
The only flaw in that logic is that if the engine is designed to run on 87 that's what you should run in it. Premium fuels will do you no good and will just cost you more.The octane rating of the fuel is just it's measured ability to resist detonation. It is not something that increases performance on it's own. If the particular engine in question is designed to operate on 93 octane fuel then increasing the octane rating above 93 will have no effect. If the fuel you are using is 87 octane but the engine is designed to run on 93 and you switch to 93 the performance would increase in this example because the engine spark knock control system would detect detonation with the 87 octane fuel and retard the spark from the optimum value to prevent damage...thus hurting the power. Once the spark reaches the optimum value with the 93 octane fuel...no more performacne to be gained. In any case, the octane rating of the fuel only needs to be high enough to meet the requirements for that engine. Adding octane beyond that will not help performance. I hope this clears it up for you.
Right on.


Once I accidently added 87 to the Eldorado. I swear to god I could feel it with less power and worse gas milage.

Night Wolf
01-03-04, 02:36 AM
I run only premium in the DeVille.... but it also requires it.... I was tempted to try 89 one time (premium is 93) but didn't....it's a luxury car, it deserves the best...

....my Olds OTOH with the 3800 V6, I first put $10 of premium in it, then filled with 89, and ran that empty, now have it filled with regualr (87) and it seems to be fine, but I think it was designed for 87.... but hey, if it is fine on the cheap stuff, then the winter car will get it...... plus the 3800 has a knock sensor, the 4.9 dosn't....

davesdeville
01-03-04, 05:05 AM
My friends Saturn requires premium, but he runs it on 87. He might as well, it makes about 7:1 compression these days..

El Dobro
01-03-04, 03:22 PM
GM has never made a Saturn that requires premium. Tell him to check his owner's manual or talk to the dealer.

davesdeville
01-03-04, 06:05 PM
I was just going by what he said. Maybe hes a little :cookoo:.

Sinister Angel
01-03-04, 09:52 PM
I sure as hell wanna know when saturns started needing premium.

El Dobro
01-04-04, 02:52 AM
I have the 1998 Seville salesman technical sourcebook and it states that 87 octane fuel can be used, but performance and fuel mileage will be decreased. They figure the 1998 and up was designed to be used in foreign countries where the fuel may be crap.

davesdeville
01-04-04, 05:30 PM
Talked to my friend with the saturn yesterday, he says he was talking about his mom's car, not his. I do not know what his mom drives though... I thought it was an Astro, but that's his dads.

Scrapyard
01-04-04, 08:24 PM
High compression engines require high octane. Personally, If it has 10:1 compression I use premium. You're not gona hurt the motor. High octane has a more complete burn compared to lower octane. So you don't get "pinging" from improper burning of fuel at the wrong time. If fuel sits in the cylinder and ignites from the general heat of the motor under, say the compression stroke. The motor pings and that's what will cause damage. Your STS is probablly running 9.5:1 - 10:1 compresion. If it's at 9.5:1 that's probablly why it runs ok with 89 octane, but it could benifite from 93. Plus better gas dosn't funk up the motor as much with deposites and such so it'll keep the internals cleaner then it would with a lower grade. If you love your car, you'll spend the extra dime a gallon.