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Ive been told that while the 05 GT can takes regular unleaded gas that its a good idea to put premium in it everyonce in awhile. Anyone have any thoughts on this? It sounds like a good idea but I really dont know.
 

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Running premium may allow the timing to advance a little but there's really no advantage without being tuned for it.
 

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Unless you're running an aftermarket tune, you're wasting your money using premium.

If you do a quick search on this, I believe that there are many posts on this subject that will be very informative..........
 

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Discussion Starter #4
Thanks for the info.
 

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I only run premium fuel I have heard it is way safer engine knock wise.When I had my BMW people had cars with 300k miles on them an attributed it to things like synthetic oil and premium fuel.
 
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I only run premium fuel I have heard it is way safer engine knock wise.When I had my BMW people had cars with 300k miles on them an attributed it to things like synthetic oil and premium fuel.
Unless you have a tune that needs premium fuel i.e., 91-94...your actually getting worse performance.

Higher octane fuel = harder to ignite fuel...you actually get less performance out of it than you do with 87 octane in a car tuned for 87 octane. Running "premium" fuel will in no way help extend the life of your engine if your engine is not tuned to need it. If anything it will cause your plugs to foul more and attribute to heavy carbon buildup than normal. To high octane fuel will not ignite and burn to the same temperature as 87 will and plugs self clean around 1350 degrees. The "octane" is actually the fuels resistance to igniting (basically). 87 actually ignites easier than 94. There isn't more power in the fuel...you can just run different engine tune variables that take advantage of the higher octane of the fuel.

"premium" is not what you need. Reputable "good" gas is what you need. Stay away from the super cheap discount stations and go with Chevron, BP, 76, and the like. Still no guarantee, but odds are better your getting what you pay for.
 

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Ive been told that while the 05 GT can takes regular unleaded gas that its a good idea to put premium in it everyonce in awhile. Anyone have any thoughts on this? It sounds like a good idea but I really dont know.
Once in a while, is the key word here.

Years ago, it was a pretty common practice. You mostly ran on regular, that's all the family wagon needed. Back then, premium had the detergents and solvents to clean out the lines and the carb; regular didn't have it. So every once in a while you ran a tank of premium through it just to keep it clean.

Nowadays, premium and regular have the same cleaning ability. That practice should have gone by the way side long ago. But some people still do things only because gramps did it, and his rambler lasted 20 years.

About every 8-10K miles or so, I put in a bottle of Chevron Techron fuel system cleaner. Does it help? I don't know. But my truck has 100K on the odomoter, and still idles and runs smooth. And, it helps me sleep at night.
 

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That is the thing it is a fuel injected car with pin point tuning. The car is made for that octane. I would never run race gas in my car unless it was tuned for it. It will just cause more bad then good in the out come.

The only way I would add 91 is if you get a bad gas or some thing
 

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Unless you have a tune that needs premium fuel i.e., 91-94...your actually getting worse performance.

Higher octane fuel = harder to ignite fuel...you actually get less performance out of it than you do with 87 octane in a car tuned for 87 octane. Running "premium" fuel will in no way help extend the life of your engine if your engine is not tuned to need it. If anything it will cause your plugs to foul more and attribute to heavy carbon buildup than normal. To high octane fuel will not ignite and burn to the same temperature as 87 will and plugs self clean around 1350 degrees. The "octane" is actually the fuels resistance to igniting (basically). 87 actually ignites easier than 94. There isn't more power in the fuel...you can just run different engine tune variables that take advantage of the higher octane of the fuel.

"premium" is not what you need. Reputable "good" gas is what you need. Stay away from the super cheap discount stations and go with Chevron, BP, 76, and the like. Still no guarantee, but odds are better your getting what you pay for.
Agree... Premium without a premium tune is nothing more than a placebo.
 

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Higher octane not waste of money!

My 2005 mustang knocked like mad on 87 octane, especially in the warmer weather. 91 ocatane cured the knock. I scheduled routine appointments with Ford about this problem. They could never fix it, but oddly enough, tried, knowing that this was a "normal" condition. They always urged against using anything higher than 87. Long story short, they eventually replaced my 2005 with a brand new 2006 after scoping the cylinders and seeing damage at a mere 7500 miles. Well, the 2006 knocks just as badly on 87 octane in the warmer weather. The engineer from Ford who replaced my car still urged me not to use higher than 87 octane. I think it's bad design to "rely" on knock sensors to make adjustments for an engine which clearly can't run properly on Lawn Mower grade fuel. About performance, I have noted, and perhaps it's just me, but I have noted that I cannot chirp the tires on 2'nd & 3'rd gear upshifts while running 87 octane, but I CAN with 91 - 93 octane. In the winter months, I can get away with 87. Both my 2005 and 2006 Mustangs were/are bone stock. Oh, one other thing. Ford has offered to check my engine for carbon build up as they feel that may be an issue with the running of higher octane fuel than the car was "designed" for. I'm going to take them up on that soon.
 

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My 2005 mustang knocked like mad on 87 octane, especially in the warmer weather. 91 ocatane cured the knock. I scheduled routine appointments with Ford about this problem. They could never fix it, but oddly enough, tried, knowing that this was a "normal" condition. They always urged against using anything higher than 87. Long story short, they eventually replaced my 2005 with a brand new 2006 after scoping the cylinders and seeing damage at a mere 7500 miles. Well, the 2006 knocks just as badly on 87 octane in the warmer weather. The engineer from Ford who replaced my car still urged me not to use higher than 87 octane. I think it's bad design to "rely" on knock sensors to make adjustments for an engine which clearly can't run properly on Lawn Mower grade fuel. About performance, I have noted, and perhaps it's just me, but I have noted that I cannot chirp the tires on 2'nd & 3'rd gear upshifts while running 87 octane, but I CAN with 91 - 93 octane. In the winter months, I can get away with 87. Both my 2005 and 2006 Mustangs were/are bone stock. Oh, one other thing. Ford has offered to check my engine for carbon build up as they feel that may be an issue with the running of higher octane fuel than the car was "designed" for. I'm going to take them up on that soon.
Have you ever tried a can of Seafoam. If you have deposits that are causing the detonation, it will often reduce or eliminate it.
 

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Unless you have a tune that needs premium fuel i.e., 91-94...your actually getting worse performance.

Higher octane fuel = harder to ignite fuel...you actually get less performance out of it than you do with 87 octane in a car tuned for 87 octane. Running "premium" fuel will in no way help extend the life of your engine if your engine is not tuned to need it. If anything it will cause your plugs to foul more and attribute to heavy carbon buildup than normal. To high octane fuel will not ignite and burn to the same temperature as 87 will and plugs self clean around 1350 degrees. The "octane" is actually the fuels resistance to igniting (basically). 87 actually ignites easier than 94. There isn't more power in the fuel...you can just run different engine tune variables that take advantage of the higher octane of the fuel.

"premium" is not what you need. Reputable "good" gas is what you need. Stay away from the super cheap discount stations and go with Chevron, BP, 76, and the like. Still no guarantee, but odds are better your getting what you pay for.

All rise for the Gospel............

+1 as has been said sooooo many times before!
 

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I'm getting a fair amount of knock lately around 3k+ RPMs. I'm running a tank of 89 octane now & so far it has cut down on the knock. Based on some of the earlier posts, this is solving one problem and introducing another (deposits). Is it better to live with the knock while I hunt, tank by tank, for a good 87? Is the knock or side effects of running 89 the lesser evil?
 

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I'm getting a fair amount of knock lately around 3k+ RPMs. I'm running a tank of 89 octane now & so far it has cut down on the knock. Based on some of the earlier posts, this is solving one problem and introducing another (deposits). Is it better to live with the knock while I hunt, tank by tank, for a good 87? Is the knock or side effects of running 89 the lesser evil?
Run a bottle of Techron or Sea Foam in the tank. You may have some carbon buildup that's leading to detonation.
 

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Run a bottle of Techron or Sea Foam in the tank. You may have some carbon buildup that's leading to detonation.
Will do...I last ran some Seafoam around 5,000 miles. The car just rolled over 10,000 this week.
 

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I run Chevron 91 only and no problems. The techron does work. I have pulled plugs after using it and before , wow what a difference.
 

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I run Chevron 91 only and no problems. The techron does work. I have pulled plugs after using it and before , wow what a difference.
Was the buildup happening fairly quickly that you could tell?
 

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I never saw any build up using Chevron gas.I did on the first tank of gas the dealer put in,god only know where that came from.
 
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