Premium Unleaded Only?

[FullyAvenged]

Just recently got the 99 GTP. I know it calls for the Premium Fuel, Can I possibly do Premium every other time I fill up or should it be everytime I fill up.

[grandprixgtx00]

well...technically, you should never run lower than 91 octane in your GTP, but i know people that put mid-grade in their GTP if they know they're not going to be running any boost I.E just cruising down the highway...not passing.

personally i only run Premium, that way i know I'm not running the rist of KR

[BNaylor]

Originally Posted by grandprixgtx00

personally i only run Premium, that way i know I'm not running the rist of KR

If saving a few cents per gallon is that important by using for example mid-grade which I have done on my Regal GS and what appears to be a reasonable option is to use one range colder spark plugs. However, I'd be cautious about any pedal to the metal or any driving conditions where the engine is under a heavy load. Definitely no regular unleaded.

[GTP Dad]

Stick with the 93 octane. You may save 10 cents per gallon using the lower octane but you may spend $4000 for a new engine if happen to go wot one too many times.

[BNaylor]

Originally Posted by GTP Dad

Stick with the 93 octane.

93 would be nice if you can get it Lynn but the recommendation from GM is 91 octane or better. Most of us can't get 93 octane like found at the Sunoco gas stations back in the Northeast.

[daejuanj]

Originally Posted by BNaylor

93 would be nice if you can get it Lynn but the recommendation from GM is 91 octane or better. Most of us can't get 93 octane like found at the Sunoco gas stations back in the Northeast.

Where I live at I usually find 93 octane. I believe I I filled up with 92 one time, but I've never seen a gas station with 91.

[BNaylor]

Originally Posted by daejuanj

but I've never seen a gas station with 91.

91 octane is very common in the Western/Rocky Mountain states. That is why GM specifies at least 91 octane. Maybe seeing is believing. Reason is the higher altitudes so the oil companies can drop a few points on octane. Also, notice the lower octane level on mid-grade and regular unleaded.

BTW - I'm at 4000 feet altitude.


Top Tier Chevron

[HotZ28]

Fortunately in my area and most of the South East, we still have the choice between 93, 89 & 87 Octane. I usually try to fill-up when the fuel gage reaches ½ tank. I sometimes alternate between 93 & 89 @ fill-up, which renders the 91 suggested. Never had a KR or misfire even under heavy load & pedal to the metal acceleration! BTW, this is for the Ultra Series II VIN 1 RPO L67, not the Z, only 105 in that one. I forgot to mention, we have several stations near Road Atlanta, that have pumps available with 105 octane for anyone who wants to pay the price!

[BNaylor]

I use VP Racing 108 unleaded when I'm at the strip. KR will be minimal or nil if you are stock. Boost mods is a different issue. I run a 3.0 SC pulley on my GTP.

However, the pulley system is modular so I can switch back to the 3.25" or higher if necessary.

[daejuanj]

Of course BNaylor, I believed you. I should have clarified that I was just referring to where live in Chicago. I have yet to see 91 octane, it's usually 93.

BTW, Our gasoline is usually.
87 - 89 - 93

[richtazz]

Sunoco has tried to push that 86 octane here in Michigan, but cars run like dog-doody on it at our altitude so they stopped selling it here.

[FullyAvenged]

Yup I live in MI also and what I normally see is 87-89-93. I have been putting nothing but 93 in it but I was just wondering if it really made a differance.

[BNaylor]

Originally Posted by FullyAvenged

I have been putting nothing but 93 in it but I was just wondering if it really made a differance.

You'll never really know for sure until you run a KR check with a scan tool capable of reading out accurate KR at all driving conditions since KR will vary at times even if you are stock. But here is some anecdotal info that is very recent and I could pull up a bunch of old posts over the years that are worse going as far as blown engines. This guy is running regular unleaded brand unknown.

http://www.automotiveforums.com/vbul...d.php?t=898029

[GTP Dad]

93 is quite common in PA with some stations selling 92 octane as their top fuel grade. I have seen some 94 octane at certain Sunoco stations but it isn't common. 91 is sufficient but the owners manual on my 97 specifically stated premium fuel of at least 93 octane. Obviously GM didn't intend for the car to last long enough to see another octane reduction. Oh well, one day we may have a hard time finding 87 Octane if things don't change!

By the way Bob how much is the 108 racing gas per gallon?

[BNaylor]

Originally Posted by GTP Dad

91 is sufficient but the owners manual on my 97 specifically stated premium fuel of at least 93 octane. Obviously GM didn't intend for the car to last long enough to see another octane reduction. Oh well, one day we may have a hard time finding 87 Octane if things don't change!

What page was that on Lynn? That data was quickly revised by GM and superceded 10 years ago. On subsequent owner's manuals it clearly states 91 octane or higher. For example the '99 owner's manual in which the OP has 91 octane is listed.

Originally Posted by GTP Dad

By the way Bob how much is the 108 racing gas per gallon?

It varies depending on which specific formula you decide to get based on your application. StreetBlaze, C10, Motorsport XXX, etc. It was $5.50 per gallon with a minimum bucket size of 5 gallons. And the octane specified is more technical spec wise. There is Motor Octane, R+M/2 Octane and Research Octane. For example on Motorsport 109 unleaded:

• Motor Octane: 101
• R+M/2: 105
• Research Octane: 109