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How harmful is 87 Octane?

7K views 65 replies 31 participants last post by  ChiTwn_TBSS 
#1 ·
I have heard that the stock tune has a low octane table to pull timing in cases where low octane has been used to prevent pinging. Is this true? The reason I ask this is because I am talking to a guy who is thinking about selling his SS and in conversation found out that he has run nothing but regular in his truck since he bought it new. The truck is completely stock and has the stock tune.
Has this caused any damage? What are your opinions? Thanks!
 
#9 ·
I disagree. You will also lose fuel mileage as a car that is designed to run on 93 will get even worse fuel economy on lesser octane. Thus making any money saved at the pump negligable as you will be going more frequently.
 
#4 ·
My opinion is he's a ruh-tard :) hehe

But idk the answer to your question. All I know is the manual says don't do it.
 
#13 ·
The real thing would be how often did he "get on it" with that low octane. It will pull timing for sure but the effect is worse when stomping on it. Knock? How does it sound when driving it? Did he change oil regularly with Mobil 1? Maintenance records? Kind of a toss up until you research more into it.
 
#19 ·
The truck is in great condition. From talking to him I think he didn't realize what he exactly had. He said he bought the truck because of how good it looked and that it stood out on the lot amongst the other trailblazers. I have not driven it yet...he is still undecided on whether or not he wants to sell.

Thanks for all the opinions!
 
#21 ·
As they say... "You have to pay to play". Not worth saving a few pennies when the end result isn't good IMHO..
 
#23 ·
There is a guy I know who bought a '06 TBSS new back in 06. He traded in his old Astro van for it. He got it because he liked how it looked and can still tow his snowmobiles. He has run nothing but 87 octane since day 1. For what it's worth, he's a GM certified tech. I would bet that the TBSS you are considering is just fine, just like my freinds with almost 50,000 miles on it.
 
#39 ·
I have over 64000 miles on my '07, how many miles do you have on yours?
When the snow is up to your ass and you can't even drive the speed limit, why would you wast money trying to squeeze every horse out of your engine?
Once the weather breaks, I'll be back on the 190 proof gas,(EC) and running my tuned ECM and TCM.
:burp:
 
#30 ·
It's makes you wonder if he was using 87 octane gas was he using regular 5w30 oil and not synthetic?:dunno:
 
#32 ·
well hate to say it but your friends an idiot, why buy a performance suv designed for 91+ to only run 87 and save wat maybe 80-100bucks a year. it may not affect the car at the time but lets see his truck with 70-100k miles and sees who smiling then. i'll never understand why people would cheap out on the two most important things on a car gas and oil that the differences in price is hardly anything when u think about it
 
#33 ·
#36 ·
#38 ·
Sorry, here is a copy/past:

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Service Information
2008 Chevrolet TrailBlazer - 4WD | Chevrolet TrailBlazer Owner Manual | Service and Appearance Care | Fuel | Description and Operation | Document ID: 1561442
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Gasoline Octane
If the vehicle has the 4.2L L6 engine (VIN Code S) or the 5.3L V8 engine (VIN Code M), use regular unleaded gasoline with a posted octane rating of 87 or higher. If the octane rating is less than 87, you might notice an audible knocking noise when you drive, commonly referred to as spark knock. If this occurs, use a gasoline rated at 87 octane or higher as soon as possible. If you are using gasoline rated at 87 octane or higher and you hear heavy knocking, the engine needs service.

If the vehicle has the 6.0L V8 engine (VIN Code H), use premium unleaded gasoline with a posted octane rating of 91 or higher. You can also use regular unleaded gasoline rated at 87 octane or higher, but the vehicle's acceleration could be slightly reduced, and you might notice a slight audible knocking noise, commonly referred to as spark knock. If the octane is less than 87, you might notice a heavy knocking noise when you drive. If this occurs, use a gasoline rated at 87 octane or higher as soon as possible. Otherwise, you could damage the engine. If you are using gasoline rated at 87 octane or higher and you hear heavy knocking, the engine needs service.
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