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Discussion Starter #1
Hi guys,

When I bought my car the salesman told me I should use “supreme” (91octane) and I never stopped to think about it.

I went through the manual and although I'm sure it's in there somewhere I couldn’t find what the recommended fuel type is. I’m going to gas up today and I’m wondering if I should continue giving it 91.

Once again thanks in advance ;)
 

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I put 93 octane in my 3.5 but that is only because I have it setup that way through the predator, so before that I always but in 87 octane and had no problems with it.
 

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When I got my 300, the first tank of gas I put in was the "cheap" stuff and things seem to run just fine. The owners manual for my 3.5l says that the recommended gas is 89 octane, which is what I have been putting in since.
 

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When I got my 300, the first tank of gas I put in was the "cheap" stuff and things seem to run just fine. The owners manual for my 3.5l says that the recommended gas is 89 octane, which is what I have been putting in since.
Bingo, the owners manual recommends 89 which I did for 60,000 miles. In preparation to moving to Italy I started putting 87 in and haven't noticed any issues at all with the car. I'd say 91 on a stock 3.5L is a waste of money.
 

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Discussion Starter #5
That's what I was thinking too, I think I'll stop using it at least until I get the Diablo Predator :D
 

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I've had my 3.5 Touring for a little under two months, and use it to commute my hour and fifteen minute ride to work everyday. So needless to say with the gas prices the way they are, I have to fill up quite often...and I've put 87, regular stuff, in everytime! I'm not doing anything high performance with the car as of now (except maybe passing all the grandma's on the North East Extension) and I haven't noticed anything out of the ordinary. So for what thats worth :)
 

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hmm, i would think it does "matter" but that also depends on your definition of matter.

the numbers indicate ( the short version) more needed compression, air flow etc. for the fuel to burn more efficiently and effectively in a controlled environment. So I was doing 89, but when I went with a true CAI, i bumped up to 93. (and why bigger engines require higher OCT, more compression, right?)

Now, could be in my head, but i felt like the car performed better. Anyways, please anybody step in here who has more knowledge than I on the matter. I am open to having the wrong mindset here :)

now that i have the SRT8 i guess it doesn't matter as I have to use 93 anyways.
 

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Discussion Starter #9
hehe, well I fueled up at 87 and will do so until I get the predator ^^

Thanks
 

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Interesting observation on fuel grade selection.

While many vehicles indicate that only regular / 87 is recommended & quite frankly they will operate just fine under normal driving conditions.

However, there are some benefits to using premium gas IMHO.

Fact, from my personal experiences - a close friend has an Acura 1.7EL - great car & great for driving in Downtown Toronto.

She started out using regular & things were fine, I suggested to use Shell 91 premium & she did & by the second tank of premium gone through her fuel economy improved to the tune of an average of 70Km's more driving distance to one tank over using regular gas.

It also improved her power, responsiveness & efficiency - regular gas is just that - regular.

Mid grade gas is mixed at the pumps (usually a pump blend of 70% regular & 30% premium) & IMHO is a total waste of $$$$$$.

For most vehicles, filling up with premium will cost on average between $5.00 & $10.00 more to fill, but again I believe that this minor expense increase is worth it.

Higher octane fuel burns hotter internally, prompts a better spark which equals better burn / combustion of fuel & it also promotes a cleaner operating engine as carbon deposits do build up faster just using regular gas.

I have had the fuel grade debate more times in my driving career than I have fingers & toes & all opinions are welcomed, understood and more than accepted.

I just know from experience that I have, and always will use premium grade fuel no matter what car I have had in the past, have now, and in the future because it actually really does make a difference.

Just my $0.02............................
 

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Hi guys,

When I bought my car the salesman told me I should use “supreme” (91octane) and I never stopped to think about it.

I went through the manual and although I'm sure it's in there somewhere I couldn’t find what the recommended fuel type is. I’m going to gas up today and I’m wondering if I should continue giving it 91.

Once again thanks in advance ;)
IT IS SO DAMNED SIMPLE! ALWAYS USE WHAT THE OWNERS MANUAL SAYS USE. FULE, OIL, SERVICE INTERVALS, EVERYTHING. THEY PEOPLE DESIGNED THE CAR KNOW BETTER THAN ANYONE WHAT YOU SHOULD DO. PLEASE DO NOT LISTEN TO IDIOTS LIKE SALESMEN, FRIENDS, MANY PEOPLE ON HERE. ENGINEER WHO SPENT MY LIFE AROUND PROPULSIONS SYSTEMS, CAR NUT FOR OVER 60 YEARS, RACED AND MAINTAINED MY OWN. The majority of plremium fuel sold in this country goes into cars that do not need it, while the people pumping it in bitch about the price. Earlier Hemis called for premium, my '09 and 15 'midgrade and it works just great. Please, do yourself a favor, read the owners manual. To help hold ownership prices down and compete the manufacturers to all they can to get their engines to be able to use as low octane fuel as possible. Just make sure you use top tier brand, can find all about it on line, just type in top tier gasoline. Rec. fuel IS in your manual in a highly visible, type in on search on the owners disc. Also always make sure your dealer uses the proper grade oil, they tend not to read service manuals. Also do not buy their possible idea you need to bring your car in every 3 months etc., for all kinds of checkups service. Do what the book says, NO MORE, no less. Find it in the manual or on the disc and go tell your salesman he is an idiot


When I bought my car the salesman told me I should use “supreme” (91octane) and I never stopped to think about it.

I went through the manual and although I'm sure it's in there somewhere I couldn’t find what the recommended fuel type is. I’m going to gas up today and I’m wondering if I should continue giving it 91.

Once again thanks in advance ;)[/QUOTE]
 

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Bingo, the owners manual recommends 89 which I did for 60,000 miles. In preparation to moving to Italy I started putting 87 in and haven't noticed any issues at all with the car. I'd say 91 on a stock 3.5L is a waste of money.
It sure as heck is a waste of money. Where I live each step up in fuel is 10 cents, but I just finished a coast to coast trip and in some areas of the stae it is 20 to 30 cents more per gal., makes a big difference over the time a vehicle is kept
 

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Interesting observation on fuel grade selection.

While many vehicles indicate that only regular / 87 is recommended & quite frankly they will operate just fine under normal driving conditions.

However, there are some benefits to using premium gas IMHO.

Fact, from my personal experiences - a close friend has an Acura 1.7EL - great car & great for driving in Downtown Toronto.

She started out using regular & things were fine, I suggested to use Shell 91 premium & she did & by the second tank of premium gone through her fuel economy improved to the tune of an average of 70Km's more driving distance to one tank over using regular gas.

It also improved her power, responsiveness & efficiency - regular gas is just that - regular.

Mid grade gas is mixed at the pumps (usually a pump blend of 70% regular & 30% premium) & IMHO is a total waste of $$$$$$.

For most vehicles, filling up with premium will cost on average between $5.00 & $10.00 more to fill, but again I believe that this minor expense increase is worth it.

Higher octane fuel burns hotter internally, prompts a better spark which equals better burn / combustion of fuel & it also promotes a cleaner operating engine as carbon deposits do build up faster just using regular gas.

I have had the fuel grade debate more times in my driving career than I have fingers & toes & all opinions are welcomed, understood and more than accepted.

I just know from experience that I have, and always will use premium grade fuel no matter what car I have had in the past, have now, and in the future because it actually really does make a difference.

Just my $0.02............................
Your two cents worth is actually useless and wrong, and much of the performance ideas and such are in your head, no insult intended. A new Corvette will run on 87 and the performance degradation will only be felt by a pro driver. I laugh my butt off each time I see an economy car filling up with premium while the owner is bitching aobut the price of fuel. The engineers who design the car know best what fuel and oil and service intervals to use, but owners always seem to want to listen to people who can't even understand how a mouse trap works. DO WHAT THE OWNERS MANUAL SAYS, NO MORE NO LESS!
 

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I put 93 in it cause it has less methanol. and the old 3.5 don't like methanol, I get 150 km difference on 1 tank.

but the book says 89.
 

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I had a 2009 300 with upgraded V6 engine. I used 87 octane for the first 50,000 miles. At 50,000 miles I got an error
code which translated to random engine misfire. The service department was unable to solve this problem . They could make the code
go away by turning it off, but it would reappear. Tried new plaugs, tune up tec but the problem persisted. Did not seem to
effect performance except for a random miss which turned on the error light.
The problem persisted, and I rraded it in for a 2013 300. I now use 89 octane as per the service manual
I believe that the prior check engine light could have been caused by using the wrong octane fuel and damaging the engine.
 

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E1589042-C02C-419D-9131-EE4B71356D93.jpeg
The manual specifically states use octane 87 for the 3.5L engine, and goes so far as to say don’t use higher octane, as it gives no improved performance. Listen to the engineers
 

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Hi guys,

When I bought my car the salesman told me I should use “supreme” (91octane) and I never stopped to think about it.

I went through the manual and although I'm sure it's in there somewhere I couldn’t find what the recommended fuel type is. I’m going to gas up today and I’m wondering if I should continue giving it 91.

Once again thanks in advance ;)
I have run my 2010 on 89 since I bought it new. I believe 89 is the recommended octane level for the 3.5.
 
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