: Premium vs. Regular



RagingSamster
03-15-06, 11:10 AM
I was told by the dealer that my 05 DeVille runs just fine on regular unleaded, but I look up the specs on the engine and the compression is 10:1 I thought the upper limit for 87 octane was 9.5:1 or else you risk problems from predetonation. Is this true, or has technology once again blew by me?

eldorado1
03-15-06, 11:27 AM
has technology once again blew by me?

yes

:bouncy:

Ranger
03-15-06, 06:21 PM
Premium was "recommended" prior to 2000. After that compression was lower (just a tad) to allow for regular.

hogstamogsta
03-15-06, 08:43 PM
i have a 96, does this require 93 or can i use cheap stuff?

JimHare
03-15-06, 09:21 PM
My 99 ran just fine for 100K miles on mid grade. Unless your 96 is sufficiently different, I think the recommendation was 89 octane.

Even lower will not hurt the engine, the PCM will simply retard the timing a bit to forstall pre-ignition. You may simply give up a teensy bit of performance.

fpmesiIII
03-15-06, 10:38 PM
your 96 will run fine on 87

peteski
03-16-06, 12:01 AM
It will run on regular gas (slightly decreased performance) If you search this forum you'll find another thread which goes into how the engine deals with this. It is all based on knock sensors, variable ignition timing and the PCM. Northstar engine is "smart" enough to deal with this type of situation.

Peteski

Tommy Deville
03-16-06, 10:25 AM
due to increased gas prices i alternate between super and regular, every other fill up or 2, I was running regular for a while after the 5th or 6th tank the car ran lousy, pinging and tapping, I went back to super and put half a gallon of lucas in, took it on the Highway and it was fine again.

tactical64
03-16-06, 10:46 AM
I disagree with many replies in this thread, My 96 runs ok on 87, with a loss of power, but I get exactly 75-100 miles less per tank on that gas even 89 mid grade. With the 93 I can clear from 350 - 400 miles to a tank and a much smoother engine.

Patrick7997
03-16-06, 11:12 AM
Tactical64, I agree with you. My car runs like crap on 87. Serious loss of mileage and performance. 20% loss of mileage.

And you know, back in 1999, Regular was around $1.40 here, and premium was $1.60, which was around 15% extra money for the premium. At today's prices, of $2.49 for regular, and $2.69 for premium, that's only about 8% extra price for the premium. Premium is a better deal than it's ever been....

I'm getting more than 10% extra mileage alone, so, it's worth it money wise alone, to say nothing of the huge performance gain.

And before I get flamed, I'm not just a premium freak. My Tahoe gets nothing but regular 87. I tried premium in that for a few tanks, there was utterly no difference in mileage or performance. None.

In the ETC, there is a big difference. I do not know why, I just know I put premium in it now.....

Ranger
03-16-06, 12:00 PM
I ran 87 in my '97 Deville on the recommendation of our old guru. No change in performance (that I could tell), and no change in milage. Take it for what it's worth.

clarkz71
03-16-06, 03:11 PM
I don't know if my 95 Eldo is "special" but I got 430 miles on a tank of 87. And I live in the mountains in Tennessee.

clarkz71
03-16-06, 03:15 PM
Oh, and no pinging or strange noises.

Zorb750
03-16-06, 09:10 PM
I get worse mileage on 87.

2mpg every time.

AlBundy
03-16-06, 10:17 PM
My 96ESC runs fine with 87.

chevelle
03-17-06, 12:18 AM
I was told by the dealer that my 05 DeVille runs just fine on regular unleaded, but I look up the specs on the engine and the compression is 10:1 I thought the upper limit for 87 octane was 9.5:1 or else you risk problems from predetonation. Is this true, or has technology once again blew by me?

Your engine will run fine on regular.

There are many variables regarding what octane level of fuel is required. Compression ratio is only one of them. Combustion chamber design, bore diameter, cylinder head design, ambient temperature and humidity, operating altitude, etc.... all contribute to the tendency to detonate and the octane requirements. With the revised combustion chamber design of the 2000 and later Northstar engines they are perfectly happy on regular fuel even with the 10:1 CR.

Older Northstars from 93-99 will also run happily on regular under most conditions. In hot, dry weather near sea level, in particular, you might notice some loss of performance and driveability and a slight loss of fuel economy. Hot and dry exacerbates the tendency to detonate as does the higher barometric pressure near sea level. So people living in Florida or Phoenix are going to see more improvement running premium than someone in the mountains of North Carolina or the mid west in the winter. In any case the Northstar has a very effective knock control system that senses knock and retards the spark to protect the engine. No damage will occur. The spark retard required to control detonation or spark knock is what causes the slight loss of fuel economy and driveability. The Northstar has proven to be relatively insensitive to fuel octane in terms of driveablity and fuel economy so most people notice little or no difference in day-to-day driving using regular fuel.

Individual comparisons of who can use what fuel are interesting discussion but of little practical use. What works in one engine in one part of the country has little or no bearing on how an engine in another climate or altitude will accept the same octane rated fuel. You have to try it and see for yourself. Put regular in and see how it drives. Nothing can be damaged or hurt. If you don't like it, it probably has more to do with the brand of fuel than the actual octane rating so try other fuels of the same octane rating to see.

There is no such thing as "predetonation"... There is detonation (also called spark knock or ping) and there is preignition. Two completely different phenomenon. Both are abnormal combustion. Detonation occurs when the spark ignites the mixture and the end gas in the chamber spontaneously combusts due to increasing heat and pressure. Preignition occurs when something in the chamber ignites the mixture BEFORE the spark plug has a chance. Detonation is the thing usually associated with fuel of an insufficient octane rating. Preignition is usually caused by spark plugs of too hot a heat range, not fuel octane rating. Generally speaking, engines can live with detonation for extended periods of time with little or no damage. Any engine that sees preignition will selfdestruct in moments with serious holes in the pistons.

auroradude
03-17-06, 12:51 AM
I like to think of running regular in a high performance engine with high compression the same as a human being drinking deer piss. You just dont do it. First off one should not buy this car for fuel economy, and should be prepared to use extra oil (premium oil at that, dont cheap out) and use premium fuel. If you'd rather pinch pennies, drive a Honda. Those cars are meant for people to transport back and forth to their silly desk jobs anyway.

That said, if you'd rather take a chance on preigntion and suffer a little bit of HP loss when enduring a high performance acceleration manuever, and buying an extra Snickers bar with that money seems worthy to you, go right ahead and fill up with the cheap stuff, you cheapskate. :D

davesdeville
03-17-06, 05:27 AM
That said, if you'd rather take a chance on preigntion and suffer a little bit of HP loss when enduring a high performance acceleration manuever, and buying an extra Snickers bar with that money seems worthy to you, go right ahead and fill up with the cheap stuff, you cheapskate. :D

Will do, as I've done for the past year that I've owned my ETC. :D I've never noticed a drop in mileage, I've watched the spark retard PD40 and it only retards on hot days. I can take the slight performance hit during daily driving.

AlBundy
03-17-06, 10:14 PM
I like to think of running regular in a high performance engine with high compression the same as a human being drinking deer piss. You just dont do it. First off one should not buy this car for fuel economy, and should be prepared to use extra oil (premium oil at that, dont cheap out) and use premium fuel. If you'd rather pinch pennies, drive a Honda. Those cars are meant for people to transport back and forth to their silly desk jobs anyway.

That said, if you'd rather take a chance on preigntion and suffer a little bit of HP loss when enduring a high performance acceleration manuever, and buying an extra Snickers bar with that money seems worthy to you, go right ahead and fill up with the cheap stuff, you cheapskate. :D

I'm sure alot of people on this forum understand what preignition is and would not take a chance on damageing there engins to save a few pennies as oppose to buying a new or used N*. Alot of forum member's car's run fine on 87 if your's don't continue to spend your snicker money on premium. All I got to say is this Snicker tastes good.

0to60n4.5
03-18-06, 11:53 AM
Who's buying Snickers , that is not the Premium of candy bars. Are we getting cheap again . I run better on the good stuff.:)

Tommy Deville
03-18-06, 02:32 PM
I payed $2.71 a gallon the other day fro super

eldorado1
03-18-06, 04:39 PM
gas prices just shot up 20 cents in the last week here... but I'll keep getting my premium. :thumbsup:

Night Wolf
03-18-06, 04:47 PM
It's a Cadillac... the whole $2 you save on a fill up really isn't a big deal....

Rob S
03-18-06, 10:03 PM
It's a Cadillac... the whole $2 you save on a fill up really isn't a big deal....

Agreed, but to each his own. I figure if I cant afford the extra for premium, I probably shouldnt be driving a caddy. But thats just me, my car is getting the good stuff.

davesdeville
03-19-06, 07:56 AM
People who do not care about $2, please paypal $2 to MediumD#gmail.com. Thank you.

elwesso
03-19-06, 11:22 AM
If you bought a cadillac, it is assumed that you can spend the extra $200 per year on premium fuel (average based on 12,000 miles per year at 20c extra per gallon)..

THe bottom line is, the engineers have to design these cars to run on premium for cheapo owners who think that it really makes a difference in loing term costs..... if you cant pay for premium fuel, you should not drive a cadillac.. BOTTOM LINE. You will spend by far more (BY FAR!!!) on things like fast food, overpriced starbucks coffee, and so forth..

Heres another reason to run premium. Many times (id dare say most times) premium is not always superior in its octane (in fact many times 93 octane can be a real 89 octane, but thats also saying that 87 octane, could be like 84 octane, NOT good!) rating but its additive package. Premium fuels contain more additives that make your engine run better...

Read the following thread! Honestly, if I didnt have an upgraded ECU in my car that required me to run hi octane, i wouldnt run premium, howveer the deciding factor for me is the additives..... :)
http://forums.nicoclub.com/zerothread?id=161936

auroradude
03-19-06, 11:54 AM
I really doubt there is any more additives in premium fuel -- thats more of an urban legend. The premium is worth it for the anti-knock rating that our engines should be run with.

elwesso
03-19-06, 12:07 PM
I really doubt there is any more additives in premium fuel -- thats more of an urban legend. The premium is worth it for the anti-knock rating that our engines should be run with.

read the thread if you do not believe!!! Concentrate on posts by Q45tech!


Regular vs Premium may have stated octane differences but the big factor is the level of deposit cleaning detergents added to Premium.
Regular should [on a good day] contain the absolute minimum level per government spec, Premium usually contains 2 x the minimum.

It is a lot cheaper to buy the detergent [at 16-20cents per gallon increment] than to pay Chevron $8 for Techron that treats 20 gallons or BG 44K [$15] that might treat 40-60 gallons.

http://www.mobil.com/USA-Engli...2.pdf (http://www.mobil.com/USA-English/Files/Us%20Gasoline%20Map%20100102.pdf)

"The Alliance for Automobile Manufacturers twice a year takes gasoline samples in 26 U.S. cities — including Kansas City. One of the tests is for “unwashed gum,” which is an indicator of the amount of detergents in gasoline. In the winter following the EPA standard going into effect, according to AAM tests, unwashed gum levels in regular gas dropped more than 20 percent. By 2002, gum levels had declined about 50 percent. Although recent tests show slightly higher levels, they are still low.
Joe Colucci, a retired director of research and development at GM who now operates Automotive Fuels Consulting, said reducing detergent additives to the EPA regulation level was seen by some companies as a way to reduce costs.

Although detergents cost only a fraction of a cent per gallon, it adds up to an enormous sum because of the huge volume of gas sold. “They would say to themselves, ‘We'll meet the letter of the law,' and that's what has happened with much of the gasoline,” Colucci said. By 2002, the automakers say repair records suggested that the EPA standard for detergents wasn't high enough. They approached the EPA about increasing gasoline detergents, but say they were reb
Most people can't even name over 3 chemicals that are in gasoline.........there are over 100-155 different ones.
And it varies substainally batch by batch day by day from the same refineries depending on which well the base oil comes from not which country which individual well! It all gets sloshed together in the tankers but not mixed 100%.


http://www.faqs.org/faqs/autos/gasoline-faq/part1/
http://www.faqs.org/faqs/autos/gasoline-faq/part2/
http://www.faqs.org/faqs/autos/gasoline-faq/part3/
http://www.faqs.org/faqs/autos/gasoline-faq/part4/
Not to say that even the finest PREMIUM has enough detergents to keep the injectors, valves, piston tops like brand new after 15,000 miles.....but the system will be cleaner than if Regular was used.
http://www.performancechemical...xhtml (http://www.performancechemicals.basf.com/ev-wcms-in/internet/en_GB/portal/show-content_ao/content/EV/EV3/ext/keropur_com/index.xhtml)

Why I use BG44K prior to every oil change [every 90 days] to cleanup what wasn't cleaned by gasoline detergents.

"Shell Oil estimates that 60 percent of the fuel sold in the United States is at or near the “EPA minimum level of detergency” and says that has caused problems in some cars. “We have measured significant deposit buildup in certain vehicles in as little as 5,000 miles,” Shell stated in one document. Early this year, GM approached Honda, Toyota and BMW to join in an effort to improve gasoline detergent levels. GM believed that an organized group rather than a lone automaker would show the seriousness of the issue."

Polyisobutyleneamine
Polyetheramine
Polyisobutyleneamine/polyoxyalkylene
Polyoxyalkylene

auroradude
03-20-06, 07:56 PM
Ok i stand corrected lol. I didnt see them posts, but 1 person isnt really gonna sway my opinion. I need some solid proof before i'll ever agree, like a trip to the shell testing labs or when the goverment tests gasoline stations.

I never added that chevron treatment for $8 either, some of my friends do and they say i should. Now are you goign to tell me that is beneficial as well? the money part about it doesnt matter to me, i make plenty. if something is good for it and actually works, i'll buy it. Of course I get battered for doing the Auto-RX treatment that cleaned a bunch of stuff out of my engine and nobody believes me.

Night Wolf
03-20-06, 07:58 PM
People who do not care about $2, please paypal $2 to MediumD#gmail.com. Thank you.

ummm...... :bigroll:

Night Wolf
03-20-06, 08:05 PM
My father believes in using premium gas too... so much that he fills the gas cans up with premium for the tracots, mowers and other equpment around the place....

He said when he tore down the 10hp Kohler on the '68 Cub Cadet for a rebuilt because it was tired... the engine was clean... not just the crankcase, but the carb, piston, cylinder etc.... he said it was cleaner then any other tired, high hour lawn tractor engine he has seen.... part because of the routine oil changes and part from the premium fuel.

My 4.9 requires it, no knock sensor and I advanced the timing. My Oldsmobile needed regular... I ran premium in it at times, and regular... the '79, with 8.2:1 compresson ran fine on regular... it got premium sometimes, but others regular.

STS 310
03-20-06, 08:41 PM
MMMM. Snickers...

STS 310
03-20-06, 08:46 PM
Ok i stand corrected lol. I didnt see them posts, but 1 person isnt really gonna sway my opinion. I need some solid proof before i'll ever agree, like a trip to the shell testing labs or when the goverment tests gasoline stations.

That aint gonna happen so loosen up and have a Snickers.

auroradude
03-20-06, 09:38 PM
Ah, no thanks..:bigroll: Think I'll just fill up with 93 octane some more while you bananas save your measly $2 with 87. :thumbsup:

Night Wolf
03-21-06, 10:44 PM
$2/filll up...

fill up once a week...

$8/month

$96 a year to run Premium instead of regular in my Cadillac. I'll do it.

STS 310
03-22-06, 07:49 PM
I used to alternate between 91 (we dont get the 92 anymore outhere) and 89 tank for tank when I realized I wasnt saving much money.

Its all premium now.

Now if we really wana kick this post in to high gear, we can talk about whether one brand of gas is better than an other....

eldorado1
03-22-06, 08:06 PM
Shop at one of the top tier.

Chevron, Texaco, some other one...

I fill up at chevron, I can't trust Texaco's gas, it smells funny. Not ha-ha funny either, the bad funny.

STS 310
03-22-06, 09:28 PM
Whats you opinion of ARCO?

From what a person told me, (alot of refineries in the Port of Los Angeles Area and I have a few friends that work for them) most gas stations buy from the same refinery, from Chevron to the mom and pop establishments.

eldorado1
03-22-06, 11:11 PM
most gas stations buy from the same refinery, from Chevron to the mom and pop establishments.

That's 100% true.

Problem is, they all buy different blends. The top tier stations have additives that IMHO are worth it to actively seek them out.

I don't mind paying a little extra for good detergents and PEA ("techron").