Got this off saturnfans forum

[Chazb]

well i took my car in for the recall. got the update, fixed the seal problem, and the cold start problem. had the car back 2 weeks and all problems came back except the seal replacement. took the car back in a few days ago, techs "fixed" the problems again. got a phone call while car was being serviced, tech said "cold start" and "bucking" problems whe more than likely due to premium gas, (91 octain or higher depending where you are in the country), elevation, and alcohol content in gas. I was kind of shocked to hear that. I was advised to put regular unleaded gas(85 octain)in from now on. that sux for me because performance will drop. i still have the starting problem and the bucking bronco effect to this day.

anyways, im at the end of the stick with this car. way too many lil problems for my tast. im now considering to trade it in. i love the car and the performance, but cant take the many problems any more.


Put 85 octane in your redline they say.That dealership should close because they dont have a clue.

[jpapa]

Haha let's start running our car off of ethanol and see how well it likes that Where is this dealership so that I know to avoid them at all costs if I am ever in their neighborhood. I'll go check out saturnfans forum to see what the responses have been.

My thermodynamics professor this semester told us flat out that the octane ratings are basically a marketing thing to sell the different gases, and that you don't need to put the higher octane unless your car is made or programmed for it (like our RLs are). Normal cars that recommend just the 87 octane will see no benefits by running 91 or 93, that there won't be a 'cleaner' combustion or better fuel economy, so don't do it. He said that it could in fact be damaging if your car isn't made for it due to more powerful/quicker detonations. So keep that in mind with other cars that aren't designed to use the higher ratings. This is coming from a University of Michigan engineering professor that focuses his research in internal combustion engines, so I'm hoping I can trust what he tells us

[blackb15]

Originally Posted by jpapa

Normal cars that recommend just the 87 octane will see no benefits by running 91 or 93, that there won't be a 'cleaner' combustion or better fuel economy, so don't do it.

I run 91 in my Sentra. With the timing advanced, I have to run 91+ or the engine will start "pinging".

Edit: And I pick up a couple horsepower to boot.

[jpapa]

Originally Posted by blackb15

I run 91 in my Sentra. With the timing advanced, I have to run 91+ or the engine will start "pinging".

Edit: And I pick up a couple horsepower to boot.

Your car with advanced timing sounds like it's programmed to use the higher octane, so it would make sense for you to use it. I was trying to say that normal cars like regular IONS, regular Grand Prixs, etc., aren't really benefitting from the higher octanes.
Our RLs will benefit from the higher octane because the fuel management system detects what level octane you are using and adjusts the combustion and whole 4-stroke process. Once we put 87 octane in, the computer needs to adjust itself to have the engine go through the combustion process properly. That's why we'll experience the 'knocking' or pre-ignition of fuel while the engine management adjusts.

[Sp00ner]

Better gas does nothing if you're car can't use it. Car and Driver did a test, with a bunch of different cars, mild performance, luxury, daily-drivers, that kinda stuff. None of the cars made more power with a higher octane gas than what the car called for. One of them, I think it was a BMW 3 series, actually made less power with 93 octane. They guess it's because the car advanced the timing beyond it's best setting for maximum power, I think. I read this a long time ago...

[geokots]

Originally Posted by Sp00ner

Better gas does nothing if you're car can't use it. Car and Driver did a test, with a bunch of different cars, mild performance, luxury, daily-drivers, that kinda stuff. None of the cars made more power with a higher octane gas than what the car called for. One of them, I think it was a BMW 3 series, actually made less power with 93 octane. They guess it's because the car advanced the timing beyond it's best setting for maximum power, I think. I read this a long time ago...

My understanding is that cars with forced air requires a higher octane. I could be wrong but that was the reasoning behing 91 for my GTP

[Vita]

Originally Posted by geokots

My understanding is that cars with forced air requires a higher octane. I could be wrong but that was the reasoning behing 91 for my GTP

that's what he was saying, your car is made for it

[Colin]

93 or 100 is fine down in florida thats what i run most of the time. slight bucking in 1st gear in my drive way down hill no gas just coasting tho. I can live w/that if i beat srt's LOL

[Smurf]

when I first bought me 01 SC2 I was putting premium gas in it and it wouldnt run right so I took it back to the dealership and they told me to put regular gas and after I did I never had another problem with it

[jpapa]

Originally Posted by Sp00ner

Better gas does nothing if you're car can't use it. Car and Driver did a test, with a bunch of different cars, mild performance, luxury, daily-drivers, that kinda stuff. None of the cars made more power with a higher octane gas than what the car called for. One of them, I think it was a BMW 3 series, actually made less power with 93 octane. They guess it's because the car advanced the timing beyond it's best setting for maximum power, I think. I read this a long time ago...

I vaguely remember this article, but I do remember that the BMW 3 series did do worse with higher octane.

It's good to see people's experiences that actually help prove this right.