what octane are you running?

'07 1500 4 door with the Hemi. Run 87, no problems. Of course, I keep my foot unleaded...

All of the people that I have heard of that had valve failures on the early (03-05) hemi ran 87 octane or lower, at least all of the ones I read about on many searches on other forums.

I did run 87 a couple times, but that was with either a DSP or SC set on 87octane performance tune. Otherwise it was alway 89+

My manual says 89 preferred, 87 acceptable. So far I've only bought 14 gallons , but I went ahead and sprung for the 89.

I've ran 87 in my truck since I bought it not even really thinking about it. It now has about 4000 miles on it and runs great. Is it ok to switch from 87 to 89 and then back? Or is it similar to running synthetic oil and once you run 89 you should stay running 89?

89 here

RamIt22 said:

I've ran 87 in my truck since I bought it not even really thinking about it. It now has about 4000 miles on it and runs great. Is it ok to switch from 87 to 89 and then back? Or is it similar to running synthetic oil and once you run 89 you should stay running 89?

Click to expand...

There are no similarities between the two. Run whatever gas you want just dont run Diesel in it. And you can swap back and forth between conventional and synthetic oil all you want, it wont hurt anything.


Ever wonder what a synthetic blend is??? Its synthetic and conventional oil in one.




This is the first automobile I've ever owned the recommended 89. Everything else I've owned with a high performance engine in it recommended PREMIUM UNLEADED only. Never anything in between which I find odd. And the difference between 87 and 89 is so little I dont see how it could make as big of a difference as some of you say. Now 87 & 93 thats a little different. I've always been a mid grade guy so 89 is what I normally reach for but I filled up with 87 this past weekend and haven't noticed any ill effects.

If you use premium it could cause problems done the line as far as build ups and such

As taken from a magazine




High-octane gas isn't necessarily better than regular grade. It isn't somehow more pure and it doesn't go through a superior refining process. It doesn't even keep your engine cleaner, as some people seem to believe. Premium fuel is just gas that contains a mixture of hydrocarbons that are slightly less combustible than those found in lower octane gas. This might seem odd, since cars use internal combustion engines that rely on the combustibility of gasoline to make them go. So, why would you pay extra money for gas that doesn't ignite quite as well as less expensive gas?

93 here

blackout11 said:

If you use premium it could cause problems done the line as far as build ups and such

As taken from a magazine




High-octane gas isn't necessarily better than regular grade. It isn't somehow more pure and it doesn't go through a superior refining process. It doesn't even keep your engine cleaner, as some people seem to believe. Premium fuel is just gas that contains a mixture of hydrocarbons that are slightly less combustible than those found in lower octane gas. This might seem odd, since cars use internal combustion engines that rely on the combustibility of gasoline to make them go. So, why would you pay extra money for gas that doesn't ignite quite as well as less expensive gas?

Click to expand...

Because you don't want it to ignite too early. You don't want it to go bang as soon as it enters a hot cylinder which can happen if the octane is too low. This is called pinging or detonation. You only want it to ignite when the piston has fully compressed the air/fuel mixture and the spark plug fires to set off the reaction.

I believe it's 40 oct that I run. Lol


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atmotocrosser said:

Because you don't want it to ignite too early. You don't want it to go bang as soon as it enters a hot cylinder which can happen if the octane is too low. This is called pinging or detonation. You only want it to ignite when the piston has fully compressed the air/fuel mixture and the spark plug fires to set off the reaction.

Click to expand...

Exactly what I was going to add, learned this more so from dealing with motorcycles. My carbureted bike loved 87 but the fuel injected only wanted 93. Weird to me but the carb bike would cut out on high octane with hard acceleration, due to preignition.

Speaking of refineries, I haven't been able to figure out where the fuel comes from for Quik Trip and *** and Go here in OK. I run 89, but I averge a full mpg better on Quik Trip gas. This was not over 1 or 2 tanks, but comparing months between the two. Just wondering why?