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Do I need to run 93

D

Dave98SVT

CEG'er
Joined
Aug 14, 2006
Messages
124
Location
Jenison,MI
I have always ran premium in my SVT. With gas continuing to go up, I was wondering if I actually need premium. Has anyone ran 89?
 
Dave98SVT said:
I have always ran premium in my SVT. With gas continuing to go up, I was wondering if I actually need premium. Has anyone ran 89?
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The engine computer will push the timing curve out to the point where it detects trace knock from the knock sensor, then retard the timing just a bit until the knock is gone. This is an optimal running condition with premium fuel, and the one that will make the most power under stock conditions. Since the car calls for premium (91 octane or higher), anything lower will not be able to support the more aggressive spark advance settings because those fuels (such as 87 and 89) do not have the ability to resist preignition that premium does.

In sum, yes, you could do it. And no, it won't likely have any negative effect on your engine mechanically. But it will cost you a few horses, as EEC will retard the timing to keep your engine safe.
 
The knock sensor is not psychic... so there still will be ping/knock happening. That's not good for your pistons. If you need more detail... search and you'll find many threads about this same topic last year, when gas prices were higher than they are now.
 
Seriously, what is the price difference? Lets get crazy and say .25 more per gallon of premium over regular. And lets also go crazy and say the tank is 15 gallons. Thats less than $4 more per fill up, and I am wayyyy over estimating here. Even if you have to fill up weekly 12 a month is not much of a sacrifice, IMHO.

But do as you please.
 
I personally like to run Shell gas in my car but, the only one near me went out of business and my car seems to run better on Meijer gas than BP. What brand do you guys run.
 
I use exxon or citgo. Occasionally i'll run Shell but they're usually a little higher, but i stay away from the cheap stuff
 
SHOgoFast said:
Seriously, what is the price difference? Lets get crazy and say .25 more per gallon of premium over regular. And lets also go crazy and say the tank is 15 gallons. Thats less than $4 more per fill up, and I am wayyyy over estimating here. Even if you have to fill up weekly 12 a month is not much of a sacrifice, IMHO.

But do as you please.
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I don't like giving the oil companies any more money than I have too, and $.20 gallon adds up over the life of a car.
 
I figure if premium is recommended I use it. Sometimes a car with no "premium recommendation" will run better on it, such as my experience with Mystiques (Duratec). "Flat feeling" when regular used, but no harm. My neighbor tried regular in his Lincoln LS v8, ran poor and pings, I suspect the SVT would do the same with 87/89. My father used premium generally in his 1992 Sable 3.8, and managed not to blow the head gasket, we think because of lack of pinging.
 
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The bottom line is this: YOU CAN RUN 87!! This is stated in the owner's manual. The knock sensor will do its job and retard timing (you lose performance) but it will run.. The downside to this is that the knock sensor has to DETECT KNOCKING to work (which is a bad thing).

Now, compound this with the fact that your engine is NOT brand new, and most likely HASN'T been as aggressivley maintained as the (only?) 87-89 octane advocate we have (Big Jim) and you will see that its ability to "run" on regular has been severely diminished.

Aggressivle maintain it (not.. "oil change every 3000 miles" and you're good, kind of maintain) and you might be fine. OR.. pay .20 a gallon..
I'd pay it
 
both of our cars call for premium and we run it in both. I'd rather add up the change over a long time than have major failure and have to spend a ton of change lol
 
Somewhere I heard running lower Octane when cars require premium, gives somewhat worse gas mileage too. Maybe it was a hoax, but either way.. just get the premium :laugh:
 
I have been running the cheapest I can obtain for the last few years with no issue. For the planned spirited driving I will use 93 but I have been running 87 with no issues. I do have a pretty heavy foot as well and the car runs fine in my opinion. I think the engine has around 100k miles or so.
 
You do know that simply slapping 93 in there right before you hammer it isn't a good thing.. and isn't working like you think.

The strategy and timing changes aren't instant. The computer has to LEARN the change over a few drive cycles.
 
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