Mid-Grade Gasoline (89 Octane)

NickZ28

NickZ28

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So, I'm on my smoke break at work, checking gas prices, and it dawns on me...why do we have mid-grade gasoline? Does anybody use the 89 octone mid-grade? If so, what are the advantages of using that (and spending the extra dime) versus the 87 octane?
I use the 87 octane in our jeeps, the Vette and the SS get the 92 octane or higher. Someone please enlighten me as to why there is 89 octane gasoline....
 
I run 89 octane in my truck, but that's only because it's been custom tuned to run on that octane. Before tuning, I ran 87.
 
Maybe it's just in my head, but the higher octane the gas, the more pep my s10 gets, and the longer I can go between fill ups. I really need to actually document this one month. I had to stop using the 92 because that is all I used to use, but supposedly my engine isn't designed to burn high octane all the time (something about the engine cannot handle the higher heat that goes with the higher octane?!?!)

Now I use at least midgrade, I'm afraid to put the cheap stuff because it seems like the engine just spits it out faster, and I'm putting $20 in the tank in four days vs. the five I would get with midgrade.
 
Run the octane that is recommended by the manufacturer, or what your car has been custom tuned for, otherwise you are just wasting money!
 
The higher the octane the less resistant it is to burn. Higher performance cars with larger engines, or ones that might have a turbo charger create more heat inside the combustion chamber. The heat might get so high that the fuel is ignited while the piston is still traveling upwards and of course over time that can cause damage. That is call pre detonation. Common on modified turbo charged cars. So if you run 87 in your 800 HP forced induction vehicle it may the fuel may pre detonate. But if you run 93 or higher, the fuel will not pre ignite and the engine will run correctly.

Run what the manufacturer recommends, it is worth it.
 
rider9195 said:
The higher the octane the less resistant it is to burn. Higher performance cars with larger engines, or ones that might have a turbo charger create more heat inside the combustion chamber. The heat might get so high that the fuel is ignited while the piston is still traveling upwards and of course over time that can cause damage. That is call pre detonation. Common on modified turbo charged cars. So if you run 87 in your 800 HP forced induction vehicle it may the fuel may pre detonate. But if you run 93 or higher, the fuel will not pre ignite and the engine will run correctly.

Run what the manufacturer recommends, it is worth it.
Click to expand...
Exactly. Higher octane burns slower.

I only run shell v power premium in my cars. Average 18 mpg+ in both of my 400+ rwhp cars too!
 
Ive ran both 87 and 91 or whatever it is in my altima and have noticed no difference. On the fuel door, it mentions using the highest octaine for best performace. So Ive been using 91.
 
Thought it had something to do with the compression spontaneous combustion retardation as well.

In the higher performance engines they have a higher compression rate as well so you have to run higher grade or it will spontaneous combustion due to compression alone (heat as a contributor too I guess as posts above mentioned)
 
The computers in some cars will have knock sensors and will compensate for different octane. Although I rarely use 87 and mostly use 91/93, I find little if any difference in performance.
 
Yeah the mid grade is kinda a marketing thing, for people who dont want to buy the 'cheap stuff' but dont want to shell out for the "top of the line".

If your car requires premium, and you want it to perform like it should, put the premium in there. If not, put the regular.

Although some premium fuel lines ( like shell ) have more detergents to keep your fuel system clean, you are better off throwing in a can of seafoam or techron every month or two, that will do a much better job.
 
There were (might still be) a few Chrysler engines that called for 89. My Echo lawn equipment specifies 89.
 
I like to use the 89 Octane in my Dodge Ram. The Hemi just feels better and I get a little better gas mileage.
 
Higher octane = more power

If you chose to drive the same way (when i say this I mean 0-30 in the same time as you did before, as opposed to gas peddle in the same position as before) then you should use less fuel to achieve this.

You should you AT LEAST what the manufacturer recommends. I find that in Australia the higher octane fuel costs about 10% more and will take me 5-10% further, so I use it, as engines do generally run slightly better on it (maybe hahaha).

As for the mid range fuel, all marketing, as was said before, for people who don't want to be cheap but also don't want to pay for te "top of the line". Although now in Australia they make cars that have the mid range as their minimum required fuel.
 
From my reading, the difference in the octane rating is the way it is comprised to make it more resistant to detonation , thus the reducing the chance for pinging ( detonation in the intake port instead of the cylinder itself) Higher compression engines i.e race cars require higher octane (usually 110 octane or so) because if the fuel detonates before the piston is in the right position it will reduce the energy output of the engine


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89 Octane is a recommend level from some manufacturers for some of their vehicle. As an example, 1993 Dodge V8's had the 89 Octane recommendation. If you analyze why this is the case then the analogy would be asking why the majority of handballs produced today are blue and pink, but never black.

89 Octane is a product. It will be produced as long as there is a market for this grade of gasoline; just like every other grade.
 
89 Octane is 87 with some 93 mixed in. No real science to it aside from how many parts of each are mixed.

If you have a custom tune done on a vehicle to increase horsepower, you will need to use 93 octane or better because it either sees more fuel than the manufacturer specifies, has less of a window to burn properly due to advanced timing, or both. E85 is very popular in the tuning industry for its 105 octane rating but some conversion is necessary if your vehicle isn't designed to use it. Turns out it likes to eat aluminum lol.

Otherwise, use manufacturer recommendations for the fuel you use.
 
RoadRageDetail said:
89 Octane is 87 with some 93 mixed in. No real science to it aside from how many parts of each are mixed.

If you have a custom tune done on a vehicle to increase horsepower, you will need to use 93 octane or better because it either sees more fuel than the manufacturer specifies, has less of a window to burn properly due to advanced timing, or both. E85 is very popular in the tuning industry for its 105 octane rating but some conversion is necessary if your vehicle isn't designed to use it. Turns out it likes to eat aluminum lol.

Otherwise, use manufacturer recommendations for the fuel you use.
Click to expand...

Interesting info. I have also read that E85 decreases your gas mileage dramatically, but it makes great power as you mentioned.
 
I don't like the thought of using E85 which is made of corn or ethanol which is pretty much alcohol that not only attracts water/moisture ( that is the reason boats must use100% gasoline) but it will also corrode metals and eats rubber. The flex fuel cars have special plastic parts to deal with that problem


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