More for the Premium 93 vs 89 Debate
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HT4100 4.1, 4.5, 4.9 Discussion, More for the Premium 93 vs 89 Debate in Cadillac Engine Technical Discussion; In a attempt to defray the cost of fuel last week i ran 89 in the caddy , not only ...
  1. #1
    Stoneage_Caddy's Avatar
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    More for the Premium 93 vs 89 Debate

    In a attempt to defray the cost of fuel last week i ran 89 in the caddy , not only do i have ping at anything more than 3/4 throttle but i do belive the mileage is worse . Since the mileage is worse it actually avreges out to be more/same money than just running premium (not to mention excessive wear tear and carbon buildup).

    This was last week tho and i had to remove the battery twice (once for wensdays waterpump failure) and fridays powersteering pump job (excessive vertical play of shaft) so i dont have a accurate idea on what exactly happens with 89 , got a full tank of 89 in for this weeks run so we shall see exactly what happens with 89 .

    Also thinking about running base ignition timing back(retard) 2-3 degrees to see if i can get it to run on 87 , any potential problems here? im thinking jacking with the timing will cost HP (has enough power as it is for me) and will probably accelerate carbon buildup

    in the end i belive sticking with premium and lubercateing my arse before i go to the gas staion is the best way to go .

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    Re: More for the Premium 93 vs 89 Debate

    I dont like to play around with the gas rating as long as this car does not have knock sensors. I consitanly try and put Chevron 93 octane in all the time. While it is bout 2 penny's more then most places I feel that it is worth it.

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    Re: More for the Premium 93 vs 89 Debate

    i must agree with that last comment. gas prices although theyre high, to me putting in premium doesnt make much of a difference. on a full tank if i use regular its about 3 bucks cheaper than using premium.

    i figure that if im driving a cadillac, the least i can do is treat it like one.

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    Re: More for the Premium 93 vs 89 Debate

    i had a 93 deville and turned the timing back about 3 degrees and ran 87. it was silly, but it worked. i lost a buncha bottom end, but i don't really ever drive fast or race. didn't ever knock or ping. gas mileage was the same, if not a little better??? anyhow, i advance my timing on car car now and always run 93 or better

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    Re: More for the Premium 93 vs 89 Debate

    about the gas prices... i fill up every tuesday. apparently nobody in arkansas uses premium, so on tuesdays they offer premium at 87 prices! anybody else seen anything like it?! It's plum insane i tell ya! hehehe

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    Re: More for the Premium 93 vs 89 Debate

    Thats ashame, i wish we had deals like that, we once did few years back when a new hess station opened. You could get 87 for 94cents and 93 for like $1.08. Every other car here in south florida is either a Hummer or Escalade so alot of 93 is taken from the stations.

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    Re: More for the Premium 93 vs 89 Debate

    Gas Prices where i work are 175 for 87, 185 for 89 and 193 for 93, the only break that is given is on sundays where we do 5 cents off a gallon which if you think about it you would have to get 10 gallons or more to save a half a buck which i my opinion is still pretty crappy, moral here is that people can be pretty patethic when they have to wait in lines to save a few pennies. i'm talking 3 or 4 deep in lines, then come monday it's a ghost town.

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    Re: More for the Premium 93 vs 89 Debate

    premium here is at least $1.99 then it goes up from there, in Coral Gables it gets up to $2.15. Really sucks, how as a country we spend all this money (you know what im talkin bout) and we get no benifits when it comes to gas and all that money is in the gas capitol of the world.

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    Re: More for the Premium 93 vs 89 Debate

    How about 89.9 cents per liter!! $1.99 per gallon is cheap!

    Stoney, use premium. Supposedly premium burns at a lower temp required for the 4.9. However, despite all the knocking I heard when my dad ran reg. in my car for years, I've yet to see or hear about a damaged engine from it!! I will still recommend what the factory recommends though, you never know.

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    Re: More for the Premium 93 vs 89 Debate

    Ralph, maybe for you but for me Id rather be spending alot less. Hopefully this changes by the end of the year.

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    Re: More for the Premium 93 vs 89 Debate

    premium does not burn at a lower temp or slower or anthing like that. i think everybody should do a search and learn about higher octane gas.

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    Re: More for the Premium 93 vs 89 Debate

    Quote Originally Posted by LacSeville
    premium does not burn at a lower temp or slower or anthing like that. i think everybody should do a search and learn about higher octane gas.
    I've done searches on this subject just over a year ago when I took delivery of my Father's Fleetwood. You see, the engine was knocking so badly that I was concerned the pistons would bust through the hood!

    Octane is related to temperature of the combustion chamber, perhaps not as directly as one might think, but check out the second paragraph of this link from Shell oil.

    http://www.countonshell.com/products...ne_grades.html

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    Re: More for the Premium 93 vs 89 Debate

    As engines accumulate miles, they also accumulate deposits in the combustion chamber that usually increase the engine’s octane requirement. The deposits reduce combustion chamber volume, increase the compression ratio and increase octane requirement. The insulating effect of these deposits increases combustion temperatures, which can also increase octane requirement.

    I can't think that those deposits would raise the compression enough to amount to anything. deposits on the cylinder walls would very negligibly raise cylinder temperatures, IMO... i understand where you are coming form though. IMO, I just can't help but think that that page was designed to sell their brand of gas I don't think they were thinking that people would technically consider their explanation. i don't know i may be way off...

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    Re: More for the Premium 93 vs 89 Debate

    that's interesting though, i've never thought about that approach, and i know the sound you are talking about when i accidentally filled up with 87 a couple months ago. i feared for public safety! haha. i advanced my timing, so it was terrible.... i only drove straight to walmart to pick up some octane boost!

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    Re: More for the Premium 93 vs 89 Debate

    Quote Originally Posted by LacSeville
    As engines accumulate miles, they also accumulate deposits in the combustion chamber that usually increase the engine’s octane requirement. The deposits reduce combustion chamber volume, increase the compression ratio and increase octane requirement. The insulating effect of these deposits increases combustion temperatures, which can also increase octane requirement.

    I can't think that those deposits would raise the compression enough to amount to anything. deposits on the cylinder walls would very negligibly raise cylinder temperatures, IMO... i understand where you are coming form though. IMO, I just can't help but think that that page was designed to sell their brand of gas I don't think they were thinking that people would technically consider their explanation. i don't know i may be way off...
    They probably just want to sell more premium to us to make more money? Scare tactics, LOL!

    p.s. what is "AR" Arkansas or Arizona?

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