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Running less than 93 octane?

Run the premium even though your not seeing anything going wrong at first, that carbon build up will Eff you later. I ran 87 and 89 in my Mazda MP3 which said it was recommended but not required. A 8 months into me having it, the EGR took a dump along with my pre-cat getting wrecked which would've cause the entire exhaust to get ruined and eventually killing the engine. Hack up the extra couple bucks for premium and save yourself down the road.
 
winty87 said:
Run the premium even though your not seeing anything going wrong at first, that carbon build up will Eff you later. I ran 87 and 89 in my Mazda MP3 which said it was recommended but not required. A 8 months into me having it, the EGR took a dump along with my pre-cat getting wrecked which would've cause the entire exhaust to get ruined and eventually killing the engine. Hack up the extra couple bucks for premium and save yourself down the road.
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Octane difference won't do that. Additive level will. There is even a recent argument that using higher octane than needed contribute to carbon build-up. I suspect that the difference is insignificant though.
 
Big Jim said:
First, you must understand what octane is.

Second, you must know your car.

Then you can intelligently make your own decision.

Running higher octane than the engine needs provides absolutely no benefit.

Ford recommends 91 octane for the Contour SVT.

93 isn't needed unless you have made modification that impact octane.

I have compared 91 octane and 87 octane in my car several times and cannot tell the difference.

I maintain it aggressively, including cleaning combustion chambers and injectors frequently.

I made my living as a tune up technician and hot rod tuner for several years so I fully understand octane.

Your experience may differ.

I'm disappointed that my car wasn't factory tuned to better accommodate higher octane fuel as they left horsepower on the table.
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I agree- The Octane rating doesn't matter that much depending on what you have done to your motor... I usually run the 87, and then run a little higher once a month just for the sake to 'meet' the recommendations for the car...
 
A good friend of my father's owns serveral service stations (Exxon) and said that the mid graid actually has the same ammount as the premium because of the blend? so we always used to run that instead of reg 87 unleaded in out Dakota. On the other hand in my CSVT i run 91 octane, 99% of the time. if your trying to save money run nothing lower then mid grade. its the safest and cleanest blend next to premium :)
 
Personally, I don't think it's worth the trouble for $8-20 a month. If you do this, you'll feel like an ass if your engine dies, even if the grade of the fuel had nothing to do with the failure -- unless you're Big Jim.
 
Big Jim said:
Yep, that 87 octane is doing a lot of damage. 228,000 miles and growing. Must be ready to blow apart any day now.
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I wasn't being sarcastic, by the way. I would never presume to know more than you about anything Contour or automobile related -- and probably more than a few other things. But your knowledge gives you the freedom to experiment with things like fuel grades with confidence because you know your car so intimately, a freedom that most of the rest of us shouldn't exercise.
 
Desiato said:
... But your knowledge gives you the freedom to experiment with things like fuel grades with confidence because you know your car so intimately, a freedom that most of the rest of us shouldn't exercise.
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Well said. There are a lot of things I would do with my car that I would not post, just because I know enough of my car to know what can be done and what I can get away with, without hurting the car. I can't be responsible for some other CEGer's lack of knowledge of what the "breaking point" is.

In this thread's example, if the knock sensor was broken, and the owner did not know it (even though the CEL was on), using a lower than recommended octane (91) would cause "detonation" to the SVT's engine.
 
i run 87 and i have 166k and it doesnt ping or knock or anything it runs great as long as its 87 from sonoco. hess or pride the car will run like crap. i havent noticed a difference in running 87 or 93 from sonoco
 
I run no less than 89. I have gone back and forth from 93 and 89 and somewhere in between that sometimes and seen no real difference in performance or mileage. The one thing that I do find is my car HATES BP gas in all forms, 89 or 93. Whenever I put BP gas in, my car throws a code within 50 miles. I have to run the tank out, put some 93 and octane boost in to clean everything out. The CEL usually goes away within the next tank. For some reason my car only likes cheap gas.
 
before i bought the contour svt i have now (13k miles) I another i bought with 30 k miles and ran until it was totaled at 120k i used 87 and 89 gas every once in a while and never noticed anything wrong with the engine or the way it ran.. Also my MPG was very close... Now with this like new CSVT i will only run 93!
 
primalzer1998 said:
how do you figure it only makes 93.4?
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Just a guess. Most people think when it says "raises octane 7 points!" that it means it makes 93 into 100. It actually raises it .7 to 93.7 octane. 93.4 was just a random number on some "non-street legal performance!" boost I saw once.
 
primalzer1998 said:
I run no less than 89. I have gone back and forth from 93 and 89 and somewhere in between that sometimes and seen no real difference in performance or mileage. The one thing that I do find is my car HATES BP gas in all forms, 89 or 93. Whenever I put BP gas in, my car throws a code within 50 miles. I have to run the tank out, put some 93 and octane boost in to clean everything out. The CEL usually goes away within the next tank. For some reason my car only likes cheap gas.
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my car hates BP gas pumps! its not just one station is all of them around here. they over flow every time. the pump just doesn't sit right in my fill tube. never had any problems with Shell or any other pumps.
 
Dyoel182 said:
Just a guess. Most people think when it says "raises octane 7 points!" that it means it makes 93 into 100. It actually raises it .7 to 93.7 octane. 93.4 was just a random number on some "non-street legal performance!" boost I saw once.
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Aahh, was just curious. I don't really use it to up the octane as much as to clean out the fuel system of the bad fuel that my car didn't like that just went through.

SVTJON87 said:
my car hates BP gas pumps! its not just one station is all of them around here. they over flow every time. the pump just doesn't sit right in my fill tube. never had any problems with Shell or any other pumps.
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Haha, that sucks. Yeah I've never had a problem with that, but then again I never put the pumps on high, I always put them on as slow as possible, I'm rarely ever in that much of a hurry.
 
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