What octane are we using?

[CompuDav]

I run 89, usually Arco... I haven’t tried any other grade yet and probably won’t until I get the Pulsar. Using 87 may harm the engine and using 91 is a waste of money. The only thing I’ll do is periodically fill up with Chevron or something like that to help clean out the engine.

 

[Cannonball]

87 top tier here.

My opinion is that RAM recommends 89 just so they could squeeze every mpg they could during rating tests to keep their mpg ratings competitive.

89 is 10% more money to get 5% better mpg

 

[Jus Cruisin]

I'm running 87 empty and 89 towing my enclosed car trailer.

 

[Gtbrown]

I run Cenex 89 in mine, its a Top Tier fuel. Truck seems happy.

 

[PTRAM]

I run 87 and so far no problems. I have had other Rams with the 5.7 engine and run 87 in them and no problem. I had a brother who run 87 in his Ram--5.7 and it was still going strong at 125,000 miles.

 

[bgmshrm]

#2 soon as get my ecodiesel

 

[BeauxXL1200]

I run 93 octane Chevron because I run the truck in Pulsar’s performance mode. Averaging 16.8 or so in mixed city/highway driving.

 

[Cosmok]

I use 87 because I want the freshest gas possible, around here I dont see many running 89. I worry about bad/stale gas.

Someone once told me there is no 89 tank in the ground. It runs a mixture of 87 and 91/93 to achieve the 89 rating. I have no idea if it is factual.

 

[392DCGC]

I don't see much need to run 89 unless you're towing or want max performance. Truck runs fine on 87. Shouldn't be enough of a difference in fuel economy to make up for the cost increase of mid-grade.

My mom has a 2009 HEMI in her Aspen with over 250K miles. Has only ever run 87 gas from wherever she happens to stop. These trucks are obviously tuned a bit more aggressively, but her manual says the same thing - 87 acceptable, 89 recommended. No problems with her engine.

93 ONLY for me. Every fill up. Same in my 2013 in fact all my cars. Top Tier only also unless not available when traveling then I go with highest octane and best brand I can.

I dont care what anyone says I think its the best thing you can do in modern engines. You also need to make sure to really drive the **** out of it every couple of weeks. Heavy acceleration and really stand on the gas to burn out a lot of the deposits.. The ethanol in the gas and direct injection causes more deposits.

I know they say the engines adjust but the manual I have recommends a min of 89. There is no reason not to run the higher octane. Everyone has their opinion but my 13 has 100k miles on it and it runs like new until this day.

If you knew what you were talking about, you wouldn't be running 93 octane. Truck isn't tuned for 93 from the factory, so don't run it unless you get it tuned for 93.

Someone once told me there is no 89 tank in the ground. It runs a mixture of 87 and 91/93 to achieve the 89 rating. I have no idea if it is factual.

This is most likely true. No need for another storage tank and lines when you can accomplish the same thing just by mixing your low and high grade.

 

[rhill]

Ram wouldn't say 87 is acceptable if it would hurt the engine. You will only get a little more hp and possibly marginally better mpg. My last 2 Rams and this one uses exclusively 87 octane. I have pulled a 5800 lb camper from Arkansas to Seattle Wa, and from Arkansas to Boise Idaho. Never any pinging or knocking and always plenty of power. Not going to pay an extra 25 cents per gallon when I am having good results with the 87 octane.

 

[Patpenrod]

Someone once told me there is no 89 tank in the ground. It runs a mixture of 87 and 91/93 to achieve the 89 rating. I have no idea if it is factual.

Correct, that's exactly how they do it.

 

[Rammit]

I use either 87 or 89 depending on price of gas when I fill up. I haven’t noticed any difference in performance or mpg with either one.

 

[RodRow]

Debates aside, 89 every time for me. It’s what’s recommended, so I’ll throw a few more pennys per gallon in my $55k trucks. If I were unable to afford it, that would be different...but it’s a minimal impact to my wallet.
Heck, I have a glass of craft beer for more than it costs to cover the premium on 2 tanks!

 

[Deriggs007]

I really ought to ask my Dad this question. I never thought of asking. He's Cummin's lead Chemist and has been for 42 years, actually finally retiring!

The point I'm getting at is that he's had to work directly with this octane differences, performance etc with gas/diesel in various engines. The 19L, 30L, V903's, etc. Not saying he's worked directly with this engine, but if there is a 'science' I can ask if the science is legitimate or a placebo effect as mentioned and if there really are some benefits. The 2nd post of this thread states there is no real gain at all... I'll figure that out with science.

I put 87 in mine. It is a $50K truck, but I went from spending $20 every week to $45 now. It would be like $55 if I went with 89. And, I don't think I saw an advantage with 89 personally. Truck just runs nice.

 

[Saints]

I really ought to ask my Dad this question. I never thought of asking. He's Cummin's lead Chemist and has been for 42 years, actually finally retiring!

The point I'm getting at is that he's had to work directly with this octane differences, performance etc with gas/diesel in various engines. The 19L, 30L, V903's, etc. Not saying he's worked directly with this engine, but if there is a 'science' I can ask if the science is legitimate or a placebo effect as mentioned and if there really are some benefits. The 2nd post of this thread states there is no real gain at all... I'll figure that out with science.

I put 87 in mine. It is a $50K truck, but I went from spending $20 every week to $45 now. It would be like $55 if I went with 89. And, I don't think I saw an advantage with 89 personally. Truck just runs nice.

I’d be curious to hear what he has to say.

 

[Deriggs007]

Alright,

Just had a long conversation with him. He got off on a tangent about oil (that's his specialty) but anyways. So, the 2nd post of this thread is essentially spot on as well. If the engine was designed for 89, then to see all of the performance, gas mileage etc, then it's best to use what is recommended. He did state that it's common for most manufacturer's to account for differences in the quality of gas and that you may not notice a difference running a quality 87 octane.

That said, if you go to joe smoes down the road and put 87 in it and it's not a quality gas, you may notice that difference, degraded performance, sluggishness and so on where you may not have felt that difference using their 89 recommendation which was determined by all the number crunching they had to do.

He said, essentially what manufacturer's do is account for the "bad" gas - he had some fancy word for it that they use on a graph chart....and every vendor follows a specific plot chart of performance based on octane levels and design/tune the engine for the least common denominator, or that "bad" gas.

He doesn't really know our engines, but he thinks you're just fine on a high quality 87, or 89 on the small places you're not so sure about. He suggested that if I'm money conscious than to run what he calls "88" and fill up with 89, run it down to about 1/2 tank and fill it back up with 87, run it back down to 1/2, fill it up with 89, rinse/repeat and that small mixture should help for those that live in the boonies and don't have quality gas around.

 

[Cmerkert]

Alright,

Just had a long conversation with him. He got off on a tangent about oil (that's his specialty) but anyways. So, the 2nd post of this thread is essentially spot on as well. If the engine was designed for 89, then to see all of the performance, gas mileage etc, then it's best to use what is recommended. He did state that it's common for most manufacturer's to account for differences in the quality of gas and that you may not notice a difference running a quality 87 octane.

That said, if you go to joe smoes down the road and put 87 in it and it's not a quality gas, you may notice that difference, degraded performance, sluggishness and so on where you may not have felt that difference using their 89 recommendation which was determined by all the number crunching they had to do.

He said, essentially what manufacturer's do is account for the "bad" gas - he had some fancy word for it that they use on a graph chart....and every vendor follows a specific plot chart of performance based on octane levels and design/tune the engine for the least common denominator, or that "bad" gas.

He doesn't really know our engines, but he thinks you're just fine on a high quality 87, or 89 on the small places you're not so sure about. He suggested that if I'm money conscious than to run what he calls "88" and fill up with 89, run it down to about 1/2 tank and fill it back up with 87, run it back down to 1/2, fill it up with 89, rinse/repeat and that small mixture should help for those that live in the boonies and don't have quality gas around.

And if I fill up with 89 twice in a row I can score 88.33! Score for me!! Hahaha

But seriously, he's the man to ask. Great job!

 

[CompuDav]

Alright,

Just had a long conversation with him. He got off on a tangent about oil (that's his specialty) but anyways. So, the 2nd post of this thread is essentially spot on as well. If the engine was designed for 89, then to see all of the performance, gas mileage etc, then it's best to use what is recommended. He did state that it's common for most manufacturer's to account for differences in the quality of gas and that you may not notice a difference running a quality 87 octane.

That said, if you go to joe smoes down the road and put 87 in it and it's not a quality gas, you may notice that difference, degraded performance, sluggishness and so on where you may not have felt that difference using their 89 recommendation which was determined by all the number crunching they had to do.

He said, essentially what manufacturer's do is account for the "bad" gas - he had some fancy word for it that they use on a graph chart....and every vendor follows a specific plot chart of performance based on octane levels and design/tune the engine for the least common denominator, or that "bad" gas.

He doesn't really know our engines, but he thinks you're just fine on a high quality 87, or 89 on the small places you're not so sure about. He suggested that if I'm money conscious than to run what he calls "88" and fill up with 89, run it down to about 1/2 tank and fill it back up with 87, run it back down to 1/2, fill it up with 89, rinse/repeat and that small mixture should help for those that live in the boonies and don't have quality gas around.

Thanks for this post! Very informative!

One question though: I read a lot about “gas quality”. Is that something quantifiable? What makes a gas bad or good? Is it “stale” gas?

 

[Deriggs007]

Thanks for this post! Very informative!

One question though: I read a lot about “gas quality”. Is that something quantifiable? What makes a gas bad or good? Is it “stale” gas?

I didn’t have a big discussion with him about it. But stations do get their own gas from certain vendors. Stale can be part of it, but certain additives that’s added can be part, quality control of the gas and so on

In my area, Shell, exon are typically pretty high quality. Sometimes going to the local Walmart and getting 87 may not be a great idea. However, there is no way to really track where the gas is coming from for places like Walmart or joe smoes.

A tanker can come in and serve 15 different stations. That is why he mentioned it’s probably “best” to use the recommended 89 unless you know you’re getting the gas from a quality vendor.

 

[ForTehNguyen]

its recommended because thats the octane needed for all the advertised figures for hp, torque