GTP Fuel Option

souperman · #1 12-12-2007, 08:53 PM

Hello everyone. I'm a total noob to the site and I'm looking to purchase an '03 GTP. I would like to know if any of the GTP owners out there have ever tried to run their car on regular unleaded fuel rather than the recommended premium. If so, what was the result? (obviously it would be less performace, but was there pinging or knocking underhood???)...Thanks

eippermx · #2 12-12-2007, 09:23 PM

Here is what can result after long term usage....Not saying it will...But why risk losing a piston?

GTP Dad · #3 12-13-2007, 07:16 AM

Running the GTP on 87 octane is not a good idea. The PCM is supposed to retard the timing anytime it senses knock thus reducing the possibility of engine damage. In an emergency it is alright but a long term diet is not a good idea.

If you like to use the supercharger I recommend the premium. I realize it is expensive to purchase but given the alternative, as shown above, it is a lot cheaper than replacing the engine.

BNaylor · #4 12-13-2007, 08:50 AM

Visit our Tips & Maintenance forum for a detailed technical explanation. See link below.

Click here

jml755 · #5 12-13-2007, 02:14 PM

Uh,oh, I could be in BIG trouble, judging from the replies.
BUT.... I had a '96 GTP (bought new) that I ran on regular for 105K miles with no problems.
Traded it for a new '01 GTP that now has 101K miles that also has run on regular from day one. I get about 20-22 mpg overall city (rush hour) and highway. On the open road with the cruise set at 70 mph, I get 29-30 mpg. I am having some issues lately (misfiring) but I don't think that is related to gasoline type. I don't have a leadfoot, but like the boost when I need it which is not very often. I seem to recall that I was told when I bought the '96 (loooong time ago) that I didn't need to burn premium (both from the dealer and an engineer friend at GM). Am I just lucky?

souperman · #6 12-13-2007, 10:47 PM

Thanks everyone for your input and advice! jml755, I believe that the 96 GTP used the naturally aspirated LQ1 Twin Dual Cam engine which does not require premium fuel, while the 01 GTP's L67 supercharged engine does require premium fuel to prevent knock due to the supercharger (according to this forum -- Thx BNaylor!)

blazeracer · #7 12-14-2007, 06:01 PM

I've had my 2000 GTP since new, run regular unleaded all the time.. I'll run a tank full of premium once in a while when I plan on putting some miles on it with a good ole haul a$$ thrown in. But everyone is right, if you are going to use your boost, you need the octane. I have a busted piston in my shop to prove it.
I actually got my best mileage ever on regular unleaded. Had the time to kill.. Took the blower belt off (it will run that way), went from Dallas to Albuquerque at 65mph with the cruise on the entire way. Final milage, 33. I don't think the pedal ever went past halfway down on the entire trip.
On the other end of the spectrum, still on regular unleaded. Going up I17 from Phoenix to Flagstaff, 115mph, foot buried, uphill at about 4,000 feet elevation. Check engine light came on, lost power for a sec, then the engine was knocking. Limped it back to Albuquerque with the knock and pulled the head... That's the piston in my shop... LOL
So now, I still mostly use regular unleaded but stay very aware of what's in the tank. I rarely get over a bar or two of boost, which is hard to do with a 3.75" pulley, but possible. About once a month or so, I'll tank with the good stuff and open it up wide. fun fun fun.
Sooooo, yes, you can run regular unleaded, and yes, you are taking a risk.

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