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Hello to all,Currently I am putting in unleaded gas in my Armada. Gas is very high. The gas station that I have been using is AM/PM gas. I honestly beleive all gas is the same. I have 2 questions.

1) Is AM/PM gas okay to use?

2) Should I be using unleaded gas?

Thank you
 

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bz03m3 said:
Hello to all,Currently I am putting in unleaded gas in my Armada. Gas is very high. The gas station that I have been using is AM/PM gas. I honestly beleive all gas is the same. I have 2 questions.

1) Is AM/PM gas okay to use?

2) Should I be using unleaded gas?

Thank you
Had to do a search to find out what AM/PM gas was. Looks like a gas vendor, not type of gas like gasahol. All gas theoretically should be the same if rated with the same octane. Some have additives to help clean your motor. In reality, some stations have contaminated gas, lying gas meters, leaky tanks, etc. If you aren't haveing any problems with gas from a particular station, I'd stick with it.

Second, unleaded is fine. Our SUVs were made to run on just about anything and will adjust themselves to the octane of the gas electronically. If you put super in, you should realize an extra 10 hp over regular. As long as you have no Knocks, etc. go for it.
 

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bz03m3 said:
2) Should I be using unleaded gas?
Its all unleaded. The panty hosers, as Car and Driver calls them (marketing guys from Proctor and Gamble that went to Detroit, but I digress :eek: ), have called them different names. But basically you get from lowest to highest octane Regular Unleaded, Mid-Grade Unleaded, Premium Unleaded. So yes, you should use unleaded. A leaded gas would surely muck up your engine. Maybe you can buy that in Mexico, I don't know.
There are multitudes of gas requirements by state,some by location and time of year, so the exact mixture of gas you get can be different all over the country, or the State of Cal. for that matter. Bottom line, what TribleBlack said ....If you aren't haveing any problems with gas from a particular station, I'd stick with it...
I'll second that motion. I buy gas at Costco or Safeway (Grocery Store) myself.
 

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92TripleBlack said:
If you put super in, you should realize an extra 10 hp over regular. As long as you have no Knocks, etc. go for it.
that is totally false. you will notice no gains with higher octane gasolines. your ecu is mapped to run with 87 octane and that is what it will do no matter what octane you put in. At the MOST you MIGHT notice an increase in fuel economy but it will probably be negligable and not worth the extra money. also, you raise your octane level so that you DONT knock.....knocking is the early detonation of the air fuel mixture in the cylinder.....if this is occurring it could be for many reasons....but the higher the octane the higher the combustion point for the fuel which makes it harder to ignite unlike lower octanes.....this is why forced induction vehicles (turbo's/superchargers) usually REQUIRE higher octanes, so that they dont knock
 

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On average the difference between low grade and high grade gas is about 20 cents per gallon in my area..Filling up with 25 gallons saves you five bucks.Put that money in the bank and save for a new engine.
Any high performance engine making the horsepower they do should have high octane fuel in them.Add in a towing factor or upgraded exhaust or intake you would crazy to skimp on the fuel.Just my opinion on the topic.

P.S.-I didn't buy it for the gas mileage.
 

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Well,
92TripleBlack does have a valid point though.
By using higher octane fuel, you or the computer can advance the timing on the camshaft. Buy advancing your timing just to the point of where it starts to knock, that maximizes hp.

So it is totally reasonable that running 92 octane vs. 87 in the Armada can yield an additional 10 hp. If you were correct, then why would any car mfg spec in premium gas?

Bottom line, the higher the octane, the more power you can get out of it. As long as timing is adjusted.
 

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The computer can advance the ignition timing, but it can't advance the camshaft timing on the 5.6 engine.
 

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andy said:
Well,
92TripleBlack does have a valid point though.
By using higher octane fuel, you or the computer can advance the timing on the camshaft. Buy advancing your timing just to the point of where it starts to knock, that maximizes hp.

So it is totally reasonable that running 92 octane vs. 87 in the Armada can yield an additional 10 hp. If you were correct, then why would any car mfg spec in premium gas?

Bottom line, the higher the octane, the more power you can get out of it. As long as timing is adjusted.


still false....unless the ecu can detect the octane difference, which it cant, and then adjust the intake/exhaust cam timing, which it cant, you will not yeild gains from higher octane fuel...it would be stupid to advance to where you start to knock....that would be like running your engine to where it would start to throw a rod..that is rediculous to even think of......higher octane doesnt do anything exctra unless the ECU is programmed to use it.....do some research before you say what you think is right, as oppossed to what is right.....i dont think it is fair of you to give peopel who do not know better false info because you think its right
 

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higher octane can actually be BAD for your car that requires a lower octane:


http://chemistry.about.com/library/weekly/aabyb100401.htm


Origin of the 'Higher Octane is Better' Concept
Higher octane gasoline did reduce engine knock in older engines that used carburetors to regulate the air/gas mix. The older engines could not regulate the air/fuel mix going into the engine as efficiently as a computerized fuel injector. A carburetor in need of adjustment could cause too much fuel to be mixed with the air, which meant the gasoline would not burn completely. The excess gas soaked into carbon deposits and caused a premature ignition of the gasoline from the heat of the engine cylinder. The premature ignition made a sound that came to be known as 'engine knock.' When this happened, people would change to the higher octane/slower burning gasoline to resist the premature burn, thus minimizing the knock. Upping the octane was beneficial then, but engines and gasoline formulations changed.

Since the mid-1980s engines use fuel injectors with computers to accurately control the air/fuel mix over all temperature and environment ranges. The accuracy of the fuel injectors and computers is based on using the recommended gasoline for that engine. Most cars are designed to burn regular unleaded gas with an octane rating of 87. If the vehicle needs a higher octane rating this requirement is noted in the owner’s manual and usually under the fuel gauge and by the gas tank.

Gasoline Factors That Matter
The quality of gasoline and the additive package usually affect the rate of engine wear more than the octane rating. Basically what this means is that it matters more where you buy your gas than which grade you purchase.

Regular Unleaded Gasoline
The recommended gasoline for most cars is regular 87 octane. One common misconception is that higher octane gasoline contains more cleaning additives than lower octane gas. All octane grades of all brands of gasoline contain engine cleaning detergent additives to protect against engine deposit build-up. In fact, using a gasoline with too high of an octane rating may cause damage to the emissions system.

• Gasoline and Octane Ratings - This article defines octane ratings and provides an overview of how gasoline in made.


Mid-Grade Gasoline
The octane ratings 'regular', 'mid-grade', and 'premium' are not consistent. In the United States, for example, one state may require a minimum octane rating of 92 for premium gasoline, while another may allow an octane rating of 90 to be premium. Check the octane rating on the yellow sticker on the gas pump rather than relying on descriptive labels.

• The Low-Down on High Octane Gasoline - Includes information about the inconsistency of ratings across the US.


Premium Gasoline
Certain high performance engines benefit from use of high octane fuel. For other engines, using a fuel with a higher octane rating than the vehicle requires sends unburned fuel into the emissions system and catalytic converter. This puts unecessary stress on the emissions system. For some vehicles, a rotten egg smell coming from the tailpipe signals use of too-high octane gas.
 

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Malik112099, you can argure this all you want and present links to websites, but the fact still remains that almost all car mfgs have systems in place for some kind of variable timing like Hondas VTEC.
There are many other factors like altitude that affect detonation. I have been an engine tuner for 25 years and there's a reason we run much higher octane fuel for racing.
It's only logical that different grades of gas produce different performance levels. Or we would only have one grade.
I have dyno'd over 200 cars and tests were clearly done to show engine output by changing octane and timing. This is as obvious as 1+1=2

I have never stated that higher octane is better. I am only stating that there is a sweet spot that depends on many factors. Higher altitudes require lower octane, period. Do some research and you'll find out. If your engine is knocking, you should put in higher octane fuel.

I don't want to get negative on this very positive forum, but I have been doing this for many years and your articles on gas quality don't mean squat.

Go dyno your armada with 85 octane, and then re-run the same tests with 92 octane. Then superimpose both graphs into one. The 92 octane graph will clearly be above the 85 octane one.

You can't argue real world results.

I'm surprised you would argue such a simple thing.

You forgot to highlight this statement from you're own article, "Premium Gasoline:
Certain high performance engines benefit from use of high octane fuel"
 

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andy said:
Malik112099, you can argure this all you want and present links to websites, but the fact still remains that almost all car mfgs have systems in place for some kind of variable timing like Hondas VTEC.
There are many other factors like altitude that affect detonation. I have been an engine tuner for 25 years and there's a reason we run much higher octane fuel for racing.
It's only logical that different grades of gas produce different performance levels. Or we would only have one grade.
I have dyno'd over 200 cars and tests were clearly done to show engine output by changing octane and timing. This is as obvious as 1+1=2

I have never stated that higher octane is better. I am only stating that there is a sweet spot that depends on many factors. Higher altitudes require lower octane, period. Do some research and you'll find out. If your engine is knocking, you should put in higher octane fuel.

I don't want to get negative on this very positive forum, but I have been doing this for many years and your articles on gas quality don't mean squat.

Go dyno your armada with 85 octane, and then re-run the same tests with 92 octane. Then superimpose both graphs into one. The 92 octane graph will clearly be above the 85 octane one.

You can't argue real world results.

I'm surprised you would argue such a simple thing.

You forgot to highlight this statement from you're own article, "Premium Gasoline:
Certain high performance engines benefit from use of high octane fuel"
the armada engine is NOT a high performance engine....please present a dyno for the armada to prove this. you HAVE to run higher octane fuel for racing because those engines are either NA tuned or FI tuned...both require higher octane ratings to prevent detonation......that is the main reason.....a high performance engine runniing lower octane WILL knock (STi's, Evo 8's, SRT-4s, etc) REQUIRE a higher octane due to the performance of the engines...this is to protect the engine, not to get more power out of it.....higher octane gas will produce the same hp figures as the ebay "chip" will...




also....not every car mfr has every engine with variable timing....this shows how much you dont know...and not all variable timing is like VTEC either...do some research
 

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Well I'll leave this alone. I think the other members of ClubArmada can make their own judgement.
 

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WHAT DOES A LOW OCTANE VALUE MEAN, TO ME?
In the absolute worst case, if the fuel is too low octane, it may spontaneously ignite before the spark plug fires due to thermal rises from the heat of compression or from hot spots in the cylinder itself. This kind of ignition is called pre-ignition (as opposed to knocking) and is a pathological case which will just turn an engine to scrap. Diesel fuel is low enough octane that mixing it with gasoline can cause pre-ignition!

What usually happens, and what we usually call knocking or pinging is that the fuel/air mixture does not ignite before the spark plug fires but does ignite spontaneously after that. The sparkplug fires and this causes an immediate, rapid, rise in combustion chamber pressure. This causes fuel on the other side of the flame-front to ignite before the flame-front reaches it. In turn, this causes combustion chamber pressure to rise even more rapidly. The result is an explosion inside the combustion chamber as opposed to the desired rapid burning.


WHAT DOES A HIGH OCTANE VALUE MEAN, TO ME?
A high octane rating ensures that it takes a REALLY hot ignition source to ignite the fuel (such as a spark plug or the flame-front itself) and not just the rise in pressure & temperature that's a result of normal combustion. Note that the thermal rises in the cylinder are in direct proportion to the compression ratio of the engine (more below). The higher the compression ratio, the higher the octane of the fuel that's needed.

Again, if the mixture in a gasoline engine ignites before the spark plug fires, we call that "pre-ignition." Pre-ignition can damage an engine before you finish reading this sentence. To reiterate, what we're really concerned with is called "knock" and that's the spontaneous ignition of the fuel-air mixure ahead of the flame-front as a result of the rise in cylinder pressure caused by the onset of ignition (caused by the firing of the spark plug).

http://www.prime-mover.org/Engines/GArticles/octane.html
 

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Gas type and hp

Yes cars can detect octane - Indirectly most cars since 1996 can sort of detect octane. Most cars toay are set up with knock sensors that will retard timing when detonation starts to occur. The main reason for this is insufficient octane. As an example, high performance cars with compression ratios approaching 9.5 to 10 require 93 octane, California has a max of 91 octane, therefore, the knock sensor intercedes and retards timing. The question is whether the Armada is set up (compression and timing) to take advantage of higher octane, since it is advertised for use with low octane.

I would say a 10 hp increase might be low, at some points on the hp curve it might be greater, once again, it depends on how the Armada a/f and timing is mapped.
 

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are you people serious? do you really still think higher octane gives you HP? The ecu might be able to detect kock and retard/advance timing as necessary to counter act it, but that is NOT octane detection NOR is it a HP increase.....the manula SAYS 87 octane...dont you think if the Armada could make an extra safe 10+ hp , dont you think Nissan would have advertised 315hp instead of 305 or whatever it is? think about it....


andy said:
Well I'll leave this alone. I think the other members of ClubArmada can make their own judgement.
i thought so.........
 

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As a matter of fact Nissan does advertise the higher gas mileage rating for 93 octane fuel, it is called the Infiniti QX56. 315HP on 93 octane fuel (same 5.6 L motor as the Armada).
 

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basically the only thing you need to do is keep steady with the octane you put in, don't switch it up all the time.
 

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Roadrunner74 said:
As a matter of fact Nissan does advertise the higher gas mileage rating for 93 octane fuel, it is called the Infiniti QX56. 315HP on 93 octane fuel (same 5.6 L motor as the Armada).
um..why isnt the ARMADA advertised with 315hp then?

Wow...what you dont realize is that Nissan uses the 3.5L V6 in the 350Z and the G35... in the 350Z it makes 287hp, in the G35 it makes 298hp ... wow same exact engine but different hp figures....its called a returned ECU/engine ... do some research.....


The manual in the QX56 says 91 octane.....

The Armada and QX56 has a comp ratio of 9.8:1 ... sothat means the heads havent been changed and neither has the pistons..so guess what!?!?!? Differently tuned ECU!!!!!!!!!! try this......get a QX56 ECU and swap it out with yours, get higher octane and i bet youi will have 15 more horses
 

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Malik112099,
There is this thing called marketing. Don't believe al the specs you see out there.
Infiniti does not want to position the Armada and QX56 with the same power rating.

You basically just stated something that makes you look like ass.

You stated the Armada and QX56 have the same compression and have different HP ratings because the QX56 uses higher octane fuel.

Stop slamming other people til you got your facts straight.
 
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