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  1. #1
    Sr. Apprentice
    Join Date
    Jan 2006
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    Mountains of Utah
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    34

    Default Is mid-grade gasoline necessary? [Expired Topic]

    I've been running my 454 on mid-grade forever. Is it really necessary? How much power will I lose switching to regular? I use the Burb primarily as a tow vehicle for a 7500 lb. trailer.
    1999 GMC K2500/454 CID which is used primarily to pull an 8000# travel trailer about 10K miles/year. 4WD w/eletronic transfer case.

  2. #2

    Default

    One of the news magazine shows (dataline?) did a test on it. They say that you will lose no power at all. Only in rare circumstances will a vehicle that is designed to run on standard octane gasoline get much performance enhancements using a mid-grade octane gasoline.

    Steve
    10 Chevy Traverse LT AWD
    02 Chevy Trailblazer LS (110K+ miles - loaded except for 4WD - WRECKED!)
    99 Chevy Cavalier LS (105K+ miles - commuter car)
    78 Chevy Suburban Silverado (454, 3/4 ton)
    62 GMC 3/4 ton Pickup (350 police interceptor)

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  3. #3
    Master Mechanic Dr_Zero's Avatar
    Join Date
    Mar 2006
    Location
    Sunny Florida
    Posts
    706

    Default

    At some stations I have been to they have only 87 and 93 and that is it.

    Guess they use that extra tank for more 87
    My trucks!

    1996 GMC Suburban SLT
    1997 GMC Yukon SLT

  4. #4

    Default

    My brother in law is a chemical engineer. He went over with me what octane really is, and it's pretty technical when you get down to it. However, for the most part the higher the octane the faster the gas evaporates, therefore the engine can complete the cycle quicker with a higher percentage of fuel burned up in the exhaust gas return.

  5. #5

    Default

    The vast majority of cars and trucks on the road are designed to run on 87 octane. Once you start increasing the compression ratio in the engine, you need to upgrade to the higher octane ratings. Take my Contour for example... It is a 95 with the 2.5 liter v6. The owner's manual specifically states that anything higher than 87 isn't really necessary. However, when you take into consideration the 140k miles worth of carbon build up on the pistons and in the heads, the car really does benefit from 89. So much so, that there is a clear "seat of the pants" difference between the cheap stuff and the midgrade. Try this, run the current tank almost all the way out (make sure you can get to the gas station though, DUH!). When you get gas, get a half tank of the cheap stuff. Run around on that for a couple weeks to see if you can tell a difference. If there is no loss of power and no pinging or anything, save that extra dime a gallon and buy cheap.

  6. #6

    Default

    I've always been told that unless your owners manul states you should run higher octane you don't need to. If you try running 87 and you don't hear any pingging you'll be fine. I'd also be very suprised if you can tell the difference in power. Let us know what you do and if you can tell the difference.

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