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anyone using premium gas ?

1M views 2K replies 423 participants last post by  paulrondelli 
#1 ·
yes or not worth it
 
#3 ·
Not worth it if you are looking to improve your mpg, but it is worth if you use it from time to time to "clean" the injection system (injectors, valves, combustion chamber, etc).
I say this because I used it twice and the result in mpg was not better than what I had with regular. I will use it from time to time though (for maintenance purpose).
 
#4 ·
I use premium because it says right in the manual "premium fuel will provide improved performance" (pg. 354 (2nd printing)). Plus my station two blocks away from home has ethanol free premium.
 
#6 ·
I use to think that gas was just gas but not any more. Now that i know more about it and how it works it makes sense and now i get it.

I use to get quick trip gas because i thought since it gets more buisness it would have the fresh fuel but after a few data logs ive decided im not going buy from them any more. I tried a tone of different fuels and finally found a fuel my car likes and ive been running it for a few months now.

This is what bad gas looks


And this is what the gas im using now looks like


With bad gas you rknock sensor detects knock and retards your timming. Good gas you can really wind the timming up with no knock and it improves performance.

IMO its worth the extra money. You can do your own testing but ill bet you will come to the same conclusion. You may not really feel it but you can see with the datalogging what it is actually doing.
 
#16 ·
Not to rag on you but your datalog is inaccurate to say the least.

Gotta do a log from start up to 55mph cruise and take a time stamp from both at the same time stamp.

One log has idle load and another log has driving load. Knock is almost always retarded slightly under normal driving load.

Even though the logs are cool that you posted it would make a difference to have a 55mph time stamp on both logs to see the difference. That way same Load same intake air temps same everything except for the gas.

But I will say this. Good quality 87 will beat a poor quality 91-93 all day.

Now a good 91-93 will also be better then a good quality 87. Is it worth .20 cents more for the small bit of performance your factory tuned car will get..

Simple answer... No

But this is coming from someone that needs premium in 2 of my 3 cars lol.
 
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#9 ·
This also brings up the question..which brand of gas is better? Do you find that different brands are better than others? So far from my findings I get the best fuel mileage if I stick with Shell Regular. Chevron/Texaco second. If I go with any other brand, my gas mileage seems to go down a little.

I also bought the Focus so I didn't have to burn mid grade or premium gas. My previous car (2002 Jetta) ran sluggish if it burned regular.
 
#12 ·
Its true in a way, stock the car is "tuned" to run that gas. I believe they retard the timming to allow the cheap fuel to run ok in it.

You start to tweak it with a tune and you bump the timming way up and then the cheap gas starts to cause knock and then the car backs off the timming like in the pictures i posted.

When you get a tune it says premium fuel only and this is why because there IS a difference. It burns better, cleaner or something and im sold on the better gas now.

Why does the cheap fuel cause knock and what is it they put in it that does it? i dont know but i like my car so im not going to put junk in it if there is better stuff right next to it.

A few weeks ago i went to a cheap mom and pop gas station and i filled up with their premium because i was about out and knew i couldnt make it to my regular station. I swear i thought something was wrong with my car. It lost some of its zip i wasnt sure what was wrong it didnt run rough or anything it just didnt have the same zip it did.

After that tank was done i filled up with my normal 92 premium from the BP near the airport i usualy go to and i instantly felt the difference.

If i ever get in a pinch again with fuel im using just what i need to get back to the regular station and thats it.

Their premium must be low grade or something it just wasnt right.

I even had Tom tell me once after i posted a datalog and he asked me what fuel i was using because it was junk and it wasnt the same stuff i posted in an earlier log he adjust the tune to. This was early before i found a good fuel my car was happy with. The junk fuel was from quick trip at that time.
 
#13 ·
I started a thread about this a while ago that turned into a war, the general feeling for those that used it is YES it makes a difference in the 2012. It says so in the manual that premium gas will result in better performance. I get 4-5mpg better while running premium than I do on regular. Plus since the tank in the Focus is so small, even a 30 cent price difference is only a few extra bucks, worth it just for the extra cleaners they put in the premium gas too. (All IMO, feel free to say I'm a stupid kid who loves giving their money to oil company's)
 
#14 ·
I run premium fuel and I do get better mileage with it, but since it costs more it ends up cancelling the savings out. I feel like the car runs better with 93 octane in the tank opposed to 87. I also find Shell to have the highest quality fuel in my area so I stick with them as much as I can.
 
#15 ·
I've run premium since the beginning so I can't do a comparison. But I've had no knocking or shudder or any other problem reported here so I'll stick with premium. I figure this is a 12:1 compression engine that's gonna like the anti-knock compounds in higher octane gas. And the manual says as much. With 2500 miles on the clock I'm getting about 36 MPG in 90:10 highway-city driving, flat roads, low traffic, 60 to 65 depending on conditions.
 
#17 ·
Well i dont care to change peoples opinion really. I feel and with the SCT and the datalogs i can see the results. Anyone can do it themself, i dont really care to run a lower grade fuel to prove what i believe any more.

I know the logs arnt identical but i was pointing out that the engine has a knock sensor and if that sensor detects engine knock it will retard the timming which will lower performance. If lower grade fuel causes knock and retard timming how can it be better to use that fuel?

Even if its a slight improvement in performance IMO every little bit helps with this car.

I paid $200. for a CAI that had little improvement, $400. on a new header and exhaust with little improvement and then $420. for yet again little improvement. After all that i maybe gained 5-10hp so IMO the gain i notice with the premium isnt much compaired to what ive already put into the mods.

If i can feel the difference thats worth it to me.
 
#37 ·
If lower grade fuel causes knock and retard timing how can it be better to use that fuel?
There is much more to fuel than octane. Different brands use different additives, such as detergents, lubricants, surface protectants, etc. 'Top Tier' brands use much more cleaning agents than required by law, and they will keep the engine running better, longer.

Thus, using a good (e.g., 'Top Tier') 87 octane fuel is better than using a crappy (e.g., oxidized, off-season, no-additives) 93 octane.

You are incorrect in your statement about causing knock. The Focus' engine does not knock when using 87 octane because it adjusts the timing. Of course, it is not getting as much power as it could get with a higher octane fuel, but that is of small importance compared to the cleanliness and life of the engine.
 
#19 ·
One problem with Premium around here lately is the price.
Like Regular is $3.07 But mid level was $3.24 and Premium was $3.41
I do not know why the others are so much more.. Or is is like a 'sale'? on Regular.
But with that much increase.. i stick to Regular.
I do try to keep what is in the tank a little over Regular with a partial fillup of Premium every third partial fill.
(I usually fill it at 7 gallons or so)
Shell or Mobil gas only.
 
#20 ·
I usually fill mine with regular from the local Husky/Mohawk. 87 octane and consistent quality fuel. Where as the other station's in town the quality seems too vary greatly depending on the tanker load.

I have had some fillup's when I've used the other stations and the engine will be all over the place severe bogging car deciding too go rev. happy, etc.

Imho, this car is more touchy about needing good quality fuel than most.

Also little known fact but one of the pollutants the cat is designed too remove is N2O or Di-nitrogen oxide so shell enriching their fuel with nitrogen leaves more available nitrogen too form the compound because nitrogen does not burn so it actually makes your cat work harder.

As for their claims of reducing carbon build up your engine shouldn't be seeing too much significant carbon build up unless it's running rich. So benefit's for a DD are pretty negligible. But it does offer some frightening disadvantages.

Replacing a cat can cost oh $3000.00 or more which is kind of ouch inducing.
 
#22 ·
My Findings.
Premium 95 RON Worse Fuel Consumption, Less Low End Torque, Better Power at High Revs
Regular 93 RON Better Fuel Consumprion, More Low End Torque, Worse Power at high Revs

High Octane Gas has a higher % of Retardants to combat Pre-Ignition.
 
#23 ·
I use 93 and have found a bit of an improvement from 87. Its a little more pricey, but when you only have a 12 gallon tank, its not a huge extra expenditure.

I'm coming from a 98 BMW 740i that I fed premium and had a 20 something gallon tank, so its still much cheaper then what I used to pay. Plus I'm only a semi decent stick driver, and am getting closer to 400 miles to the gallon then 300 now.
 
#28 ·
I've seen those favorably running 91 octane and those who have stuck with 87. I'm the middle-of-the-road guy who's running 89 and have seen welcomed improvement. Is this the best of boths worlds? Better performance and still reasonable cost?
 
#29 ·
Running premium fuel allows the engine computer to advance the timing thus resulting in more power on the lower end torque curve, the burn time for higher octane fuel is also longer resulting in more power.
It would be interesting to see some dyno tests done with regular fuel and premium fuel.
Any of you that used to race will remember what quicker advance curves did for cars.
 
#34 ·
Adding advance does not necessarily mean more power. To get max power and efficiency maximum cylinder pressure needs to occur approximately 20 degrees after TDC. To much timing will hurt power just as much as too little.

Back when cars had distributors and springs/weights/vacuum controlled the advance curve the engineers didn't have the CAD tools to design and model engine designs that are available today. Quite often you couldn't establish the ideal advance curve because of poor combustion chamber design and inconsistent manufacturing so they established safe limits. This allowed the enthusiast to tune for their needs and make a significant improvement.

Today designs are very well optimized before the first piece of metal is machined and there is much less room for improvement.

A muscle car era bug block mopar needs upwards of 40 degrees of advance to make max power. The current generation Hemi, LS or Mod Motor makes max power with less than 30 degrees of advance and runs to much higher rpms.
 
#30 ·
99% of the time the gas is cut with ethanol to raise the octane, or the other 1% of the time additives that have vastly lower energy content than gas. Go look at the threads about people complaining about their MPGs dropping in the winter -- that's when ethanol content in gas is increased. Even if higher octane helped, you would have to see a 10% improvement in fuel economy for it to save you any money. That's a tremendous increase in efficiency, something Ford would have considered. Hell, most manufacturers switched to 5W20 to squeak a little bit more out of the engines. Ford put in radiator shutters to get an extra 3% efficiency -- why wouldn't they want a car that pulls down 30mpg in the city cycle and 42mpg on the highway? Even if people ended up using 87 and getting 28/38 instead, it would still make for great numbers in advertisements. Look at it another way; see the people running E85 and see what kind of mileage they get out of it. E85 is right around 96 octane (RON+MON/2) -- if higher octane = better mileage then logically E85 would be what everyone is filling their cars with instead of E85 being a cheap way to skirt CAFE ratings or for people that convert their cars for the massive power gains that are available. No one ever converts for fuel economy and actually gets it.

Will it make more power? Possibly, in situations that you have the engine running under a heavy load for extended periods of time because the engine will have knock issues. The compression ratio is extremely high in these engines and even in day-to-day stuff you'll have the occasional ping/knock. If you take it to an HDPE event, premium fuel is a good idea. Same goes if you're towing or load the car down in the summer months.

Any increase in economy is going to be from being conscious about getting better MPGs and being easier on the pedal. There's also the chance of carbon deposits building up quicker, but that highly depends on what additives are being used. Some cause it, some have a negligible effect. It's too soon to tell how these engines do with carbon buildup but virtually every other direct injection motor on the market has issues so it's something to consider.
 
#38 ·
No it won't. It might keep it from being retarded but it won't advance it beyond what the engine was tuned for. Plus an engine needs less timing advance at low RPMs than at high RPMs. The engine needs the most timing advance at light load cruising when the throttle is barely open. Under this condition the cylinder does not fill with air/fuel efficiently so the spark has to happen sooner to ensure max cylinder pressure occurs at the approx 20 degrees ATDC i mentioned previously.

In the old days distributors had mechanical advance that was strickly rpm dependent, more rpms, more advance. They also had vacuum advance that added more timing in high manifold vacuum conditions such as light load cruising.
 
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