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Original owner ran 87 octane..Bad?

KoreyGTX

KoreyGTX

New member
Hey,
Pretty new here as i just bought my first GP last week. It's a '99 GTX.
The guy I bought it off of (which is also the original owner) ran 87 Octane in it it's entire life until now. I'm aware that the car was designed to use premium fuel, and am wondering what effects being run on 87 for 9 years could have caused? Should I be worried about this? I assume I should start running 91 octane in it?
One more question..Is it harmful to switch back and fourth between grades of fuel for testing purposes (eg fuel mileage).
Any help is much appreciated as I'm super pumped to get some miles on her.
Thanks
 
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As long as you don't have any chipped pistons from it I'd say your fine. I wouldn't advise running 87 octane again unless you don't go WOT through that entire tank. The lower octane will exponentially increase your KR, which will increase the chance of you grenading a piston.
 
"WOT" ?

Alright, and i dont really know if a piston is damaged unless i rip it apart or something goes boom?
 
dang thats a pretty rare car. and well if the guy babied the car, it should be good. arent the gtx's already intercooled??? i dont much about them. if it is intercooled your good cause i dought you have any KR. they say to use higher grade fuel to fight off KR.
 
blowfishRus6 said:
dang thats a pretty rare car. and well if the guy babied the car, it should be good. arent the gtx's already intercooled??? i dont much about them. if it is intercooled your good cause i dought you have any KR. they say to use higher grade fuel to fight off KR.
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No GTX's came intercooled. I think your thinking of the GPX concept which iirc was supposed to have an intercooler.
 


You should be fine. The computer commands lowered timing when low octane fuel is being used, to protect the engine.
 


Thanks guys, I'm liking this forum. Lots of help!

I should probably start running a higher octane fuel though I suppose. Even going to 89 would help i think. Or maybe I should just suck it up and pay the extra $7 or so a tank for 91.
 
KoreyGTX said:
Thanks guys, I'm liking this forum. Lots of help!

I should probably start running a higher octane fuel though I suppose. Even going to 89 would help i think. Or maybe I should just suck it up and pay the extra $7 or so a tank for 91.
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i dont know how it is where you live but 91-93 is only 20 cents more than 87 here.

so lets say you have a completely empty tank.

.20 x 16 = 3.20. however, youll rarely get more than 14 gallons at a time, so its more like an extra $2.80 every tiem you fill up from e.

2.80 x 52 = $145.60 (assuming you have to fill up once a week, i get over 400 miles on a tank of gas)

a new motor from ed is going to cost at least 1k, so you make the choice. is it worth an extra $150 a year to insure that your motor wont blow up?

hope that helps put it in perspective. :th_biggrin2:
 
yeah, i only drive ~5k miles per year and get 400 miles per tank, so maybe $50-$60 a year more for premium? even if u drive alot more, it amounts to a few cents a day
 
yep. the small price to pay for the required gas far outweighs the price of having to swap a new motor in because of trying to save a few buks.
 


True true. I can suck up the $$ issue. As long as its not too late after it running on 87 for 9 years.

AS far as a difference in price, its about 10+ cents more per liter here for premium. So at about 65 liters to fill up thats $6.50 more per fill up. But liek some of you said, its cheaper then buying a new engine
 
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