I was wondering:

Would there be any problems derived from using 98 (or even 100) octane in the '05 GT?
I have a 2004 Volvo S60 turbocharged (2.5 litre, 210 hp) and I normally use 98 octane (sometimes 100 octane, when in Germany). I get better mpg and performance compared to when using regular, and no signs of overwearing.

I don't see why doing the same in the GT would cause any problems, but anyway... has anybody else thought of it ?

 

Hello nighbur

A car made for ex 93 octane want benefit from using higher octane, only cars like yours high performens car will benifit using higher octane just like you diskribe.

Best regard Lennart

 

If you want the truth...I did a speech on Octane back in School...and higher octane fuels DO NOT help your car in any way unless you are pulling serious horsepower. In a 300hp car, it will help minimaly, but to be honest...Its not woth the extra $$$. 100octane in $4.00 a gallon in my neck of the woods, and I wouldnt even consider it for my '65 retsomod that pulls 300horsies. 93 octane maybe if the price was right, and I planed on doing some racing, but not just to drive around. Its not going to hurt anything but your wallet by using 100+ ratings.

 

Louie,

The rating for fuel in Europe differs from the US, our 98 is the equivalent of 94 in the States. It wont cause any problems but you could use a flash tune to see any real benefit.

 

I wouldn't use a anything higher than 89 octane on a stock 05 Mustang w/o a tune.

I don't think using higher octanes is beneficial w/o a tune.

I doubt using higher octane than 89 will cause damage other than financial.

There's always high grade aviation fuel like JP7 but advancing the timing sufficiently to take advantage of it is questionable and running at such a high compression will almost certainly ruin the engine.

 

as long as it is unleaded you should be okay

 

Best fuel for the GT is 87 octane as recommended by the manufacturer. No point in going to anything else. There is a post out there that goes into this alot and that the motor is not meant to burn higher octane, such as 93. Even with a tune you could still have problems in the long run.

 

I have been told that High Octane fuel 93-91 burns slower than 87 and can leave unburn't fuel inside the engine combustion chamber and on the valves. Maybe a hotter plug or computer flash will help but be careful just putting in high octane. A friend of mine had an F-150 brand new and always ran Amoco 93 octane because it was very clean but had major performance problems with the engine after about 3-4 months. The Ford tech said the fuel was the problem. After doing a complete injector power cleaning, he went to the 87 octane and it ran fine .

 

Does using the high octane (98 or more race gas) really help when youre doing high performance driving, like a track day?

 

Higher octane ratings simply mean that the fuel has more resistance to knocking, i.e. it'll run at a higher compression ratio without premature detonation. From what I've heard, the 05 is computer is tuned so that there is a bit of wiggle room in the knock tolerences, so running on 89 or 93 AKI gasoline might get you a few extra horsepower, because the engine can run a bit more aggressive timing. However, on the vast majority of cars running any higher octane gasoline than that recommended by the manufacturer is a waste of money.

And 98 octane in Europe is 98 Research Octane Number, which is probably 93 octane if it were rated by the US method (Research + Motor/2).

 

an issue of 5.0 a few months back did a dyno test saying that 91 octane did make nearly 10 more horse power than regular 87 octane on an 05 GT........anyone rember that?

 

Ahhh the age old "Octane debate"! This gets batted around every year or so and most of what I've read tends to say that on an UNmodded vehicle the best bet is to go with the factory recommended octane rating - from a reputable fuel dealer. Using higher octane than called for is at the least a waste of $$'s (especially in today's market) and at the worst can adversely affect the performance of your engine as it's ECU is programmed for a certain octane level and can compensate somewhat for other octane levels - but not always enough - which can lead to issues down the road.

No expert by any means just trying to pass along what I read that seemed credible.

Now on a modded engine that's anyones guess and I'm running 91 octane as that is what my new tune calls for.....by the way where are you guys getting 93 & 94 octane - I've never seen this in Cali.....we only get the 91.

 

Here is an old link for you!

http://forums.bradbarnett.net/index....opic=13318&hl=

kc

 

Higher octane DOES NOT give your horsepower.

/thread

 

That's because you guys on the left coast get watered-down premium. Most of the country gets 93 as premium. I'm in southeastern Illinois, and I know we have 93 octane premium in these parts because I'm posting from the refinery where we make it .