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YOUR RESEARCHBrand of Gas ?
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ethanol content of gas
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I haven't done it for my 4S yet, but with my STI I monitored my knock sensor and timing, and found I achieved less knock and the best fuel economy on Shell 91, from what I read the increase in knock and diminished performance is due to the ethanol content of gas.
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I have the repair bills and sediment-filled jar of gasoline to prove it.
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But I run Shell with some kind of nitrogen additive and the fuel system and the engines of both of my cars do not seem to have suffered any from running Shell.
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No matter what brand of premium I run, the car goes like a raped ape.
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ethanol content of gas
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I haven't done it for my 4S yet, but with my STI I monitored my knock sensor and timing, and found I achieved less knock and the best fuel economy on Shell 91, from what I read the increase in knock and diminished performance is due to the ethanol content of gas.
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Here in California I use Chevron Premium(91 octane) or Costco Premium when I'm near a Costco. I've read that Costco gas also has additives to clean injectors like Chevron's Techron. Also, great price. Shell is good also.
I use Shell gasoline. 91 octane is the highest I can get also.
My only close alternatives are Conoco or Sinclair. I've heard good things about the additives in Shell gas, and it hasn't given me any problems. Also, the pumps at my local Shell allow me to completely fill my tank. It's hot or miss with the others.
BP is sold in California as ARCO. There have been several complaints over the past couple of years of too much water, causing fouling
. Just to be clear, I personally don't know anyone that had those troubles, but I stay away anyway
I use Chevron 91octane
Any top tier gasoline is ok. Here, at home/work, I burn Shell because there's a nice station real handy and its prices are sometimes (oftentimes) less than other top tier stations nearby.
But I have at other times used Chevron or Union 76, Philips 66 and a few others.
IIRC the owner manual says something to the effect if the engine reacts unfavorably to the brand of gasoline switch brands.
Based on an EVO fuel test some years back the brand may not be the problem, the freshness of the fuel may be the problem.
Thus I would modify my advice I started out with to any top tier gasoline bought from a busy station is ok.
Techron in Chevron gasoline is nice. But I run Shell with some kind of nitrogen additive and the fuel system and the engines of both of my cars do not seem to have suffered any from running Shell.
The key is and I have to repeat this is to buy a top tier gasoline. From a busy station.
It is not the cat that dictates octane, but the compression ratio of the engine. The cat doesn't care about octane just that the fuel is unleaded.
Matt
Always prefer my close neighborhood Shell. In the Seattle area... 92 Octane - but sadly with up to 10% Ethanol. My choice would be Chevron ... if they were closer and offered the $.10 discount I get on Shell using the Rewards from QFC / Freddy's were the wife spends so much at.
Here in California it's all watered down pi$$. No matter what brand of premium I run, the car goes like a raped ape. But then again, it has a Flat6 3.6 stage 2 in the back...
Paid 1.37/litre today for 94 octane at chevron. Thats pretty much all i put in her unless there isnt a chevron around...then itll be 91 octane shell.
The chevron i go to is pretty neat since its at the start of a noce sunday drive road, so lots of nice cars and bikes hit there before heading out.
Which ever station has it for the least $$$. Seriously, you will never know the difference and none of it will do any more or less damage to your engine. It is all changed to different formulation between summer/winter anyway.
There is a HESS gas station down the street that I use all the time due to Low price, 93 Octane, and the factory that they turn their inventory so fast (due to the low price).
Well, actually no. Evo (UK car mag) did a nice fuel test (admittedly a few years ago) and found significant differences between name brand and supermarket (discount) gasolines.
Sometimes the discount gasolines were good. Other times they were not so good.
The differences were attributed to the use of various suppliers by the discounters. The discount gasoline retailers rely upon cheaper gas for their profit margin and as such shop on price.
Now of course there will be the chorus that all gasolines are the same. They are not. There are allowable variations.
Then there are the variations that occur from the transportation of gasoline.
For instance pipeline transportation: Premium gasoline is sandwiched between two loads of regular. One load in the front the other behind.
Sort of surprising to me the gasolines do not mix very much.
For name brand gasolines their requirement can be that they require their load of premium fuel be pulled from the sweetest spot of that load of premium fuel.
The discounters get the dregs, so to speak.
The test found even name brand gasolines can vary in quality. This was attributed to staleness. Thus it is very important to buy fresh gas and to ensure the freshest buy from a busy station.
Next, I've run a lot of gasoline through my cars, my Boxster in particular. With over 265K miles at say an average of 25mpg that works out to over 10600 gallons of gasoline. I've run everything from Bob's Bait and Gas Shop gas to racing gasoline.
The biggest difference is between say 91 octane (the highest available where I live/drive) and 93 octane available in places where I have driven to, distant from my CA region. With 93 octane in the tank the engine's transformation is quite remarkable.
Locally the difference is in running discount gasoline bought from a busy station vs. gasoline bought from a name brand busy station is the discount gasoline has my Boxster's check engine light coming on more often.
The car's got a weak converter.
The few times I switched to a discount gasoline for extended periods of time -- when gas prices went through the roof -- the CEL would come on more frequently.
When I switched back to name brand gasoline after prices declined I noticed the CEL did not come on.
While the conditions were not lab controlled I drive the same day in day out and the climate is not that varying here for weeks or even months at a time so I'm quite comfortable that the CEL events were due to the gasoline not something else.
For the Turbo I initially fed it some discount gasoline the same as the Boxster. But when I made what appears to be a connection between the CEL events in the Boxster and discount gasoline I switched to using mainly Shell and have not used discount gasoline in the Turbo since.
But run whatever gasoline you want.
I will end with this: My advice would be to experiment and see if your engine likes a particular brand of gasoline more than it likes another.
If you notice an improvement then stick with that gasoline. That is the gasoline you should use.
There is a 76 station close to me that sells "pure gas", no ehtanol etc...It's the only thing I use, but Shell is my back up. If you go to puregas.com, plug in your zip code, you'll find all stations that sell pure gas near you. I noticed a slight increase in mileage and the car seems to prefer no ethanol.
You should use the LOWEST octane you can and not get knocking and pinging. This will give you the most power possible. Anything higher and you are wasting your money.
You are throwing your money away. Not that that is a problem. Just sayin'.
You have posted in the 996 forum. 996s have knock sensors that retard the timing to prevent knocking.
You should run the highest octane you can get & your 996 will run better with increased MPG.
I worked at Shelby American & Saleen Mustang during the emissions certification process. 2 different cars,2 different emissions engineers. Both engineers insisted upon the same fuel, Chevron Supreme.
Gasoline trucks have more than one compartment. Just because it looks like one long cylinder, it doesn't mean it's all open. If premium is sandwiched between the regular grades than there are 3 compartments in that tanker trailer.
Emission certification is a completely different issue. Requires different tuning. Without knowing why they insisted on using Chevron supreme, that statement is worthless.
All ecu's will show knock events. I should clarify my statement. You should use the lowest octane that will not knock under the circumstances you use it. If it won't knock with 91 it won't knock with 93. if you use 93 when 91 won't cause a problem you are wasting your money.
In fact if you use your car in everyday driving you can actually use regular. Yes it will retard the ignition to remove knock events, but if you don't need that power then there is no issue. Doesn't matter what car or manufacturer. You canna change the laws of physics......
I happened to read this in an old article. I don't know if I can really trust this, although it seems to have come from an expert..
"All Porsche engines are designed for premium, too, but it's not available everywhere. "Our cars must be able to drive all over the world, and so we are able to run on regular," says Jakob Neusser, director of powertrain development at Porsche's research and development center in Weissach, Germany. "You don't have to feel that a mechanical problem or anything else will happen" using regular gas, even in the highest-performance, regular-production Porsches."
http://usatoday30.usatoday.com/money...emiumgas_x.htm
This is exactly true. I use regular in my 928 when the weather is cool. 91when it warms up. I also use regular in my 04 Tuareg v8 and unless I am pulling a load the seat of the pants meter cannot tell the difference.
sigh, I wonder what the training program is like at shelby and saleen because your post makes no sense.
yes, the 996 has knock sensors. And if they aren't active on 91 octane (i.e. there is no pre-ignition or detonation and hence, no knock retard) then 91 is what you should run. If you have knock retard on 91, then 93 will benefit you.
Now then, once the car is not knocking, adding extra octane will actually lose you some power. Thats why people who put in 100 octane into stock vehicles and think they gained power crack me up.
so, to summarize, run the absolutely lowest octane you can that doesn't cause knock retard.
As to the brand, who cares. Its not like your car is gonna run noticeably different on one brand vs. another assuming the same true octane. I know, I know, now macster is gonna run in here with some 14 paragraph post about how xyz brand gave him better performance and mileage.
someone with some sense, nice.
The computer will only retard the timing if the knock sensors are active. Under gentle every day driving, you likely won't see any knock retard. Obviously at higher load and throttle openings, you may start to see it, and that would result in lower fuel economy.
If you drive gently you can run regular gas in almost anything.
Here in Calgary, we can get 94 octane at two sources: Husky or Petro-Can. The Husky supposedly has a small amount of ethanol, but my car seems to like it better. When I get the Petro-Can product, it sets off an odd yet meaningless CEL.
I definitely notice the difference between 91 and 94...
How do you find your P-car runs on Shell V-Power 91? Both Husky and Petro have 10% ethanol which I find runs like crap. I haven't done it for my 4S yet, but with my STI I monitored my knock sensor and timing, and found I achieved less knock and the best fuel economy on Shell 91, from what I read the increase in knock and diminished performance is due to the ethanol content of gas. So even though Shell was only 91, since it has 0 ethanol it performed better than Husky or Petro. I really wish we could get Chevron 94 with techron in AB with 0 ethanol, that s**t be magic
Brand of Gas ? is the title of this thread. I stated a few facts relevant to the subject of this thread for 996s. The gas filler door of USA 996s says to use a minimum octane of 93. Any recommendations contrary to Porsche's for usual fuel selection is false economy at best.
Perhaps your redundant posts on the same concept would be more valuable on a Prius forum.
My local BP, Shell, and Mobil have 93 octane. I usually opt for Mobil at the nearby truck stop because they have the best prices. ($3.57 for 93 octane today
)
yawn. Porsche can require whatever it wants. If your particular car doesn't pull timing due to knock on 91 octane, running 93 is pointless.
But then again, being a shelby employee (LOL) you probably knew that.
Its irrelevant what brand, is it that difficult to understand that?
Learn from those that know why. Many here think they know how an engine and the related systems work, but all they know are just myths.
Is it possible that the damaged converter reacts better to a slightly detuned engine that is result of using too high of an octane or perhaps Shell gasoline has less energy? Anything is possible if you believe hard enough.
3. My gas isn't better for your car; it s just more expensive.
Oil companies spend lots of money explaining why their gas is better than the competition's. Chevron's gas, for example, is fortified with Techron, and Amoco Ultimate is supposed to save the planet along with your engine. But today more than ever, one gallon of gas is as good as the next.
True, additives help to clean your engine, but what the companies don t tell you is that all gas has them. Since 1994 the government has required that detergents be added to all gasoline to help prevent fuel injectors from clogging.
From Smart Money's "10 Things Gas Stations Won't Tell You"
http://www.smartmoney.com/spend/rip-...ell-you-19750/
I was not implying that the 2 different grades of gasoline are not separated in a tanker truck. Of course they are. They reside in different compartments.
Octanes 87 and 91 are in two different tanks. Medium grade is "made" at the station by blending the two other grades.
That is absolutely wrong.
One should use the recommended octane grade. With this grade the engine controller can run the most advance whenever it can which will deliver better performance, more power (though not oodles), but more torque too. In one test 20% more torque between the best and worst gasolines.
Fuel economy will be better.
And the advanced timing will lower exhaust gas temps which cuts down on engine component wear and tear.
Now there is no benefit from running a higher octane than the engine is designed for.
Except I would add that if the car is tracked if by adding racing fuel the in take octane rating jumps from say 91 to 94 when the engine is designed for 93 this gives one a bit more margin on the octane. Might point out that as engines run/age their octane requirement can go up so that 94 may not be as overkill as it would appear to be, at least on the track.
In short, with an engine designed to use 93 octane I'd rather be at 94 octane vs. 92 octane when on the track.
You misspelled nonsense.
It is under everyday driving the timing is most advanced. Under observation it is during low rpm steady speed cruising that the timing gets advanced and at which time the octane rating of the fuel becomes critical.
When you smash the throttle the timing gets retarded because the DME also unleashes a richer mixture which ignites quicker.
Run the proper grade of octane in your car, or as near as you can. The engine will run better and deliver cleaner combustion and better performance. It may not feel like you are losing anything but believe me you are.
When I get a chance to run 93 in say my Turbo on a road trip vs. the 91 I have to feed it day in and day out where I live the difference in the engine's performance/behavior is very noticeable. I really really wish I could run 93 all time, in both of my Porsches.
Once again, this is incorrect. The ECU does not know what fuel is in the car other than what it reads from the knock sensors. If you see no knock retard on 91, then going to 93 produces absolutely zero benefit. The car cannot advance the timing beyond what it is programmed for. Either it knocks and timing is retarded or it doesn't and it runs the full timing map.
If you want an additional safety margin due to high temps, continued high rpm/load/throttle opening, fine. With street driving, this is a non issue.
My goodness. You are showing that a little bit of knowledge is dangerous.
Yes, timing is further advanced at part throttle. Clearly, however, cylinder pressure and EGTs are far far lower than they would be at full load and larger throttle opening. Cars don't knock while cruising along on the highway (which uses about 35hp). They knock while climbing steep grades, towing, carrying heavy loads, or when the driver opens the throttle heavily.
now again, when you mash the throttle, cylinder pressure and EGT rise. The additional fuel in a rich a/f is used to cool the combustion chamber. As I would hope you would know, it does not get burned entirely. And yes, timing gets retarded from cruise in this instance, but it is under these circumstances when you would see knock if it were going to happen. If you do, then yes, you need a higher octane fuel.
I agree that you should run the proper grade of fuel in your car. And that proper grade is the lowest octane one on which you see no knock retard at all load and throttle opening.
If you notice a difference on your turbo, then you are experiencing knock retard. Datalog your car, it might tell you something.
When racing on the Bonneville Salt Flats in 1985, I met and spoke with Don Vesco about fuels. He told me less is more and to run the lowest octane that will not cause the motor to knock. I did, I went 148.456 MPH on my stock Honda VF1000F on the 5 mile course, fastest of any stock bike.
Don, has gone over 450 MPH.
I've made my living building, modding and tuning hot rod motors for decades. I understand motor requirements. That being said, I chuckled when my wife told me she runs regular in her Boxster and Lexus. I'm fine with it!
I generally run Sinclair or whatever is handy and cheap.
I have found that quality and maintenance of the facility counts more than any particular brand. Twice my cars have gotten badly contaminated gas from stations with old, apparently decaying tanks. One time the repair costs were over $1000 - luckily paid for the station after some evidence.
As a result I stick to newer, generally brand stations and never fill my tank while a tanker is at a station. The fill/pump process can unsettle contaminants that have fallen to the bottom of the tanks.
And not being a cheapskate with the Porsche I always use 93 octane. I also occasionally travel across town to get a tank of gas without ethanol. Hard to find. No idea if it is really an issue in a properly maintained, modern engine. Usually more an opportunity/destination when I just want to drive the 911 on a nice day.
the tanks of the gas stations have filters before the fuel reaches the nozzle.
Further, you have two in-car filters.
no real need to worry about filling when a tanker is there.
Respectfully, you are mistaken. Not about the filters necessarily, but on the possible effects of contaminated gas from old or damaged tanks. The simple fact is that this problem can occur, and it can be triggered when old, in-ground tanks get stirred up during refill.
You are assuming that old filters never wear out, that old, low price gas stations keep their facilities in pristine condition. That is not a good bet. I have the repair bills and sediment-filled jar of gasoline to prove it.
ok. I'll stick with the percentages here and say that on average, filling up while a tanker is there will have absolutely zero negative impact on your car.
your anecdote makes for an interesting counterpoint nonetheless.
Chevron all the way. I will put Costco in my boat and SUV. In CA you want to stay away from Arco/BP. If you have ever looked at a fuel filter running with that you'll know why.
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