5.7 Hemi - 87 or 89 Octane

[Rogues Gambit]

Nope. I buy a 36k truck and use 85. Was there a point you were attempting to make?

That you spend all that $$$$ and then complain about gas

But $36k is different

Also, your welcome

 

[Rob5589]

That you spend all that $$$$ and then complain about gas

But $36k is different

Also, your welcomeView attachment 38575

Where did I complain about the price?

 

[derp]

Complaining at the pump is my god given american right.

pretty much in this priority order:


Ethanol content
price per gallon
octane rating
fuel door on the wrong side for the pump that I can reach today.
fuel tank too small, refilling too often.
fuel tank too large, can't afford to top it up.
Lovebugs.
Who took the squeegee from the washer bucket.

 

[Rogues Gambit]

Where did I complain about the price?

I read it wrong, my bad

 

[Rob5589]

Complaining at the pump is my god given american right.

pretty much in this priority order:


Ethanol content
price per gallon
octane rating
fuel door on the wrong side for the pump that I can reach today.
fuel tank too small, refilling too often.
fuel tank too large, can't afford to top it up.
Lovebugs.
Who took the squeegee from the washer bucket.

Wyoming has "blue gas," which is ethanol free.

 

[derp]

Idaho has "blue gas," which is ethanol free.

add to the list about how big corn is keeping us from having adaho's superior fuels!

 

[Rogues Gambit]

Idaho has "blue gas," which is ethanol free.

I Gotta reason to visit now

 

[Rob5589]

Oops! That should have been Wyoming, not Idaho. ID may as well but I have not seen it.

 

[Rogues Gambit]

Oops! That should have been Wyoming, not Idaho. ID may as well but I have not seen it.

What's there to do over there btw?

 

[Rob5589]

What's there to do over there btw?

Hunt, fish, beautiful country. And not much else.

 

[Rogues Gambit]

Hunt, fish, beautiful country. And not much else.

As long as I can off-road, I'll be happy

 

[silver billet]

If it did Ram would require it in the owner's manual...so definitely not.

Not true at all. They already give you a warning about it in the manual, but they're not forced to say "required" anymore then they're apparently not forced to make a distinction in EPA certified MPG between a light tradesman and a heavy limited or rebel.

The original point I was making was, even with 85, there was no power or mpg loss.

Not true at all either. There is definitely a difference, the computer will be doing knock retardation and that means a decrease in power. You may not feel it, but it's there regardless. Others like myself definitely feel it under WOT or heavy loads, or even hilly highways. Remember, just because you might be color blind, doesn't mean that red doesn't exist.

To the OP of this thread; it costs you maybe 200 more per year to run the recommended octane, if you plan to keep the truck for a while then it seems like the smart thing to do would be to follow the recommendations of the guys who built the thing instead of penny pinching.

 

[doctorxring]

Modern vehicles have octane sensors. Burning lower octane gas causes the computer to retard the timing a bit. Hence a bit lower performance and a bit less MPG.

 

[parnine]

Not true at all. They already give you a warning about it in the manual, but they're not forced to say "required" anymore then they're apparently not forced to make a distinction in EPA certified MPG between a light tradesman and a heavy limited or rebel.



Not true at all either. There is definitely a difference, the computer will be doing knock retardation and that means a decrease in power. You may not feel it, but it's there regardless. Others like myself definitely feel it under WOT or heavy loads, or even hilly highways. Remember, just because you might be color blind, doesn't mean that red doesn't exist.

To the OP of this thread; it costs you maybe 200 more per year to run the recommended octane, if you plan to keep the truck for a while then it seems like the smart thing to do would be to follow the recommendations of the guys who built the thing instead of penny pinching.

The Owner's manual -

 

[Amazing93]

I'm sure you've probably considered it, but when I fill up at Costco, I blend the 91 with the 87 to get to 89, or close to it. Saves some $ and really no additional benefit to using all 91 that I am aware of.

I do the exact same thing at costco

 

[Nick814]

I run 89. Gives you no “more” power, but insures the engine wont knock and pull timing. The higher the octane the more resistance to knock. Thats all it is. This way you get the full power i paid for.

 

[silver billet]

I run 89. Gives you no “more” power, but insures the engine wont knock and pull timing. The higher the octane the more resistance to knock. Thats all it is. This way you get the full power i paid for.

This gets into semantics when we talk about "more power":
- running 91+ octane does not give you any more power but doesn't hurt your engine
- running 89 octane gives you 100% of your engine's rated power
- running 87 octane gives you a reduction in your engine's rated power
- running 85- octane will damage your engine and reduce power even further

Some may not notice the reduction with 87, but I definitely do. I also notice when I run gas with less or no ethanol, for some reason it does best on gas with 0 ethanol. My pentastar 3.6 was the opposite, with 10% - 15% ethanol giving me a light surge of power at 2800 rpms and beyond which would not occur with 0 ethanol gas.

Don't know why, and maybe I'm suffering from confirmation bias or something else is going on, but that's my observations.

 

[Raydar]

My opinion is that our trucks may run a bit better on 89 than on 87, but there is no harm in using 87.
I'm basing this on the fact that my truck didn't seem to have quite as much power, "hammer down", when I filled up the tank with 87. I'm speculating that the engine controls detected a bit of knock (long before it was "audible" to me or anyone else) and retarded the spark timing.
So... if you do a lot of passing on 2-lane roads, you might not opt for the cheap stuff. Otherwise - especially if you drive with only moderate application of the loud pedal - it's probably a wash.

With that said, Car and driver recently did a test of different cars' reaction to different octane fuels. One of their "victims" was a lower mile Charger R/T from a rental fleet. Using 87, it was down quite a bit on power, (15 HP or so?) although acceleration was only off by a few tenths. (1320 and 0-60). Take that for whatever it's worth to you.

 

[Willwork4truck]

This thread can be debated forever. If RAM recommends 89 but allows 87, then feel free to run 87. If in the mts, pulling hard, towing, giving it a lot of throttle, maybe choose 89? If driving like me, or on flatter terrain, towing nothing and having an empty bed, than 87 is fine. I draw the line at 87, won't use 85...
A station down the road has E-15 88 octane and E-10 87 octane. Now I'm no chemist and that choice does confuse me.

I do use Costco fuel at times and happily put in 91 in order to allow a mix of the next tank with 87.
I ran 87 on the highway this last weekend and got about 21 mpg, then I put 89 in on the way back and got... 21. So who knows?

 

[RamZone93]

Haven't found an answer in the forum search.

Owners manual recommends 89 Octane, but says that 87 Octane is okay also.

Aside from a (potential) slight increase in performance, and possibly MPG - is there any DETRIMENTAL EFFECT to just sticking with 87?

Regards,

Rick

I've used 89 for every fill-up since I got my truck last year. I have 17000 miles on it now. I use 89 just for the fact that the manufacturer recommends it. I'm sure they didn't just randomly recommend it, there has to be a reason. The fuel burns better at 89 and I'm sure it will have a long term positive impact to use 89 over 87. You may not see the benefits now, but you may see them down the road if you plan on keeping your vehicle for a long time.