Ultra and premium gas

[DelanoJoe]

I have a 98 Ultra with 97K miles - I got it a year ago when it had 68K. It was my moms and she drove it very sparingly and not many trips over 10 miles. Anyway I have owned two Buick Regal GS with the supercharger and never used premium. The first one was still running at 268K but the transmission died. My second one has 149K and no issues.

Is there any long term affect on not using premium in the supercharged model? I guess I never felt the need to spend more for gas for something I was sure was not a big issue.

Thanks,

Joe

BTW - My wife has a 04 rendevouz, my son has an 03 LeSabre, my daughter has an 02 Regal GS, and I have the 98 Ultra.

 

[fm9572]

You won't get full power if you don't use Premium fuel. The engine has a knock sensor. If you use standard grade gasoline, it doesn't allow the ignition timing to advance fully, to prevent detonation. The car will run fine, you're just costing yourself about 20 horsepower. If you drive slow and don't use the highway, you probably won't notice it.

This is why most newer model performance models are 'Dual Fuel' E85 compatible. E85 is rated at 110 octane. If you run straight E85, the mileage is horrible, but it lets the computer optimize for maximum performance.
Your vehicle isn't 'dual fuel' compatible, so I wouldn't recommend that. You could get away with about 15% E85 if you really wanted it to have maximum horsepower.


It's up to you. If you drive like an old grandma, you can probably get away with Regular gas. If you actually want it to run properly, and give you all of the horsepower it's rated at, then you need premium fuel for proper operation.

 

[DelanoJoe]

Well I wouldn't say I drive like an old grandma, but even with the reduced horsepower, it gets up and goes well enough for me. I might experiment and run the tank down and fill it up with premium just to feel the difference. Thanks for the answer - I was hoping it wouldn't have any adverse affects I may not have heard about.

Joe

 

[fm9572]

If you don't consider reduced power and fuel mileage 'adverse effects,' then you shouldn't be bothered by it.

 

[Kevandkaye]

If you have a display for your average and inst. mileage, give it a try. One tank with regular and one tank with premium and see what the difference is.

 

[J57ltr]

I only can speak from experience with GTP's and Ford Thunderbird SC's and if you hear any rattle (detonation) then it's not a good thing. I have driven GTP's as rental cars and put regular in them and been fine, gotten decent mileage and didn't really care for the car anyway (after all it's a rental), The SC on the other hand was fine stock with 87 octane but when I started modifying the exhaust and intake and heads raised the compression to 8.9:1, and added a 10% OD jackshaft pulley it would rattle like a coffee can full of pennies once I got above about 5psi (16psi max, 13 stock). I always ran premium after that. I am not sure about the GM's but I am sure it's like the ford where you have to empty the tank (run it out) and refill it to make the timing go back to the stock setting. Remember these things have hypereutectic pistons and they are like glass so it's best to avoid detonation at all costs.

Jeff

 

[84ZZ4]

Having seen the carnage pictures of these motors when run with regular gas, I would recommend against it unless in an emergency, and even then I'd pull the supercharger belt.

As mentioned, the pistons in these engines are not forged and are fairly weak; it doesn't take much detonation to break the ring land.

 

[Lemaster8034]

my owners manual says uses 93 PREEMEIEM OR HIGHER AND LOOK AT IN THE SIDE OF YOUR GAS TANK AND YOU WONT GET THE FULL 240 HP AND IT WILL RUIN YOUR SUPERCHARGER. I ASKED A GM MASTER TECH THAT HAS BEEN DOING IT FOR 25 YEARS AND HE SAID THE SUPERCHARGER AFTER 03 NEEDS PREMIUM OCTANE FOR THE HIGH COMPRESSION OF THE SUPERCHARGER AND HE SAID HE HAD TO REPLACE SO MEANT SUPERCHARGERS BECUASE OF LOW OCTANE GAS YOU WILL CAUSE HIGH CARBON BUILDUP AND LOSE HORSEPOWER AND DAMAGE THE INTERNALS OF THE ENGINE AFTER THE 02 MODEL YEAR. HE SAID BACK THEN THEY HAD TO REPLACE ENGINES BECAUSE OF THIS IT ACTUALLY TELLS YOU ON THE INSIDE OF YOU GAS DOOR PREM GAS ONLY. THIS GUY WAS A GM MASTER TECH II FOR 45 YEARS.i FORGOT TO TELL YOU THAT HE SAID GM DID NOT COVER THEM UNDER WARRANTY EITHER AND COSTED THE CUSTOMER A FULL ENGINE REPLACEMENT AT 4000 EACH.Yes, all Ultras are equipped with a supercharged 3800, and yes high octane fuel is required to prevent damage to the pistons. i HAVE OWNED 4 OF THESE .