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Hi
My car is 1994 4.9L Deville
I'm using 95 Octane, can i use 98 ocatne without replacing any part in the engine ?
Bye
Danny
 

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Hi Danny,

Well.. I can't give you a sure answer but I know someone else will shortly. As far as I know, it's probably bad for the catalyic converter to be using octane that high.. BUT - I could be wrong. Let's see what some of the others have to say...
 

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Yes, you can - it give slightly better gas/mileage and little improved acceleration....(and, in our country - its cleaner and better quality too :D)
 

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vanaisa's absolutely correct. Using higher octane will give you slightly better performance and MPG to the limits of the computers programming. If you bump the timing up a bit, you'll realize even better gains too.
 

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They were probably talking about racing fuels like Cam 2. They are "leaded" fuels and will destroy your O2 sensors and catalytic converters. Most tracks offer a super high test "unleaded" fuel but to be honest, I'm not sure what the octane is. I don't hang at the track much. I'll have to ask my son, he's at the track once or twice a week. :rolleyes:
 

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It's fine once in a while, I had a 94 deville in 2002. I worked at the airport next to a small jet company. I made friends with a guy there and he gave me some AVGAS (aviation galoline) It does heat up your engine if you run it too hard and too long.
 

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Where the heck can you even get 98 octane?
 

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Octane is nothing more than the fuels ability to resist knocking. Anything more than the engine needs is just a waste of money. It won't burn cleaner, produce more power or get better mileage.
 

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Where the heck can you even get 98 octane?
Hes in Israel... and I dont think anyone caught on to the fact he was probably talking about 89 Octane. In other words, he was probably asking the age old question of "will cheaper fuel hurt the car", but mixed up his numbers. I dunno... 98, 89... who knows. :thepan:

Oh look... yet another post so old the original thread starter isnt even here anymore. :rolleyes:
 

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why does everyone seem to equate high octane as "best" or "better"? It is not any "better". Just different. :banghead:
 

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why does everyone seem to equate high octane as "best" or "better"? It is not any "better". Just different. :banghead:
I dont know. The only reason you might be able to call it "better" doesnt really have much to do with the gasoline itself, but rather the "additive package" the oil companies like to boast so much about in their premium fuel. The gas itself as you said is just different.

Theres a thread in the STS-V forum right now about a guy who put 101 octane race fuel in the car and says he "felt" a 10 to 15 hp increase and it idled smoother... :rolleyes:
 

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"additive package" the oil companies like to boast so much about in their premium fuel.
That says it all. They would like us all to believe that and make them richer.

says he "felt" a 10 to 15 hp increase and it idled smoother...
Oh brother. Talk about a placebo effect. I'll bet that one is going to get interesting. I'm not even going to read it.
 

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Playdrv4me said:
Theres a thread in the STS-V forum right now about a guy who put 101 octane race fuel in the car and says he "felt" a 10 to 15 hp increase and it idled smoother...
Forced induction cars respond differently/better to higher octane fuels due to the fuel having a lower flash point, this allows advanced timing. I read an article in EVO magazine a while ago with the Golf GTi and numerous other cars were tested with 97RON; the biggest feat was that of the GTi, a gain of 18bhp and 23ft/lb torque.

In order for any gains to be seen on any car the ignition timing should be advanced. While the ECU will make the nessacery changes in order to eliminate detonation for use of lower octane fuel, should only be assumed for accidental cases of use, in most cases it will not sense an increase in octane and adjust ignition timing to take advantage of the higher octane fuel. Straight to the point, without advancing your timing it's like wasting money and unless the engine is having problems with normal premium octane fuel and is a victim of extreme carbon buildup, I suggest not wasting the money as the gains are minimum at best and with most racing/performance fuels costing over the $5/gallon mark it's like throwing money away.
 
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