Fuel Choice

Hey all. I recently bought a 2014 Ram 1500 Express. I've been reading through the manual, and I noticed with fuel specs, 87 octane is acceptable, but 89 is recommended. What do you guys think? Do those of you who use 89 find it beneficial? Is it worth it? Or will 87 cause any problems? Thanks for any insights.

I run what it says is recommended. Try both yourself and see if you notice a difference.

Sent from my SM-G900V using Tapatalk

Have a read through these, it's a common topic of discussion

http://www.ramforum.com/f44/my_experience_89_octane_gets_better_gas_mileage-101780/

http://www.ramforum.com/f44/better_mileage_higher_octane-101018/

http://www.ramforum.com/f44/87_0r_89_octane-100073/

http://www.ramforum.com/f73/required_octane-78740/

Simplify - it says 89 is recommended; therefore run 89[emoji1360][emoji6]


Sent from my iPhone using Tapatalk Pro

When I was on the stock tune I always ran 89. It's typically what, $0.15/gal more expensive? For $4 a tank, I'll just run the recommended.

I have ton ,87 and 89 octane and found no difference.

I run 89 octane

I run 89, but I tow a lot, so run 91/93 mostly. If I know I'm just going to be driving for the next tank or two I'll fill with 89, if I'm going to be towing I fill with premium.

89 and above for me. I run higher octane in there when going on long trips so I get better gas mileage. But 89 is recommended so that's the lowest I run.

89 is required on a stock truck. Why? Could it be because the PCV is vented into the intake manifold and the entrained oil vapor can cause detonation leading the PCM to pull timing?
Remember, Chrysler is not above cutting corners, and what they have done with the PCV is cutting corners. How do you fix that performance theft without costing Chrysler a dime? Simple, transfer the cost to the owner via higher gas costs by recommending 89.

Around where I live its $0.50 a gallon more for 89 compared to 87. Assuming a 30 gallon tank for easy math, that's $15 more a fill up, for maybe 2 MPG, or 60 additional miles.

My catch can paid for itself in eight fill-ups by keeping the oil out of my combustion chamber and letting me run 87.

I can more than break even buying 6 1/2 gallons more 87 at $2.30 a gallon. Its not like I'm running a street dragster after all.

Thanks for the input. I wasn't expecting to read in the manual that 89 is preferred. I'm sure it's got 87 in it right now. It's still just fuel from the dealership. And it runs fine. I couldn't help but wonder if the 89 was necessary, and if not, why was it preferred? And if it's preferred or necessary, then why is 87 ok? Would running 87 hurt your truck in any way. Etc. I found it all a bit confusing.

Thanks for the links. That was some interesting reading. Especially the article from MIT. Very credible info.

I think I will fill up with 89 next time and see if I can detect a difference.

I burn only the good stuff ie nitro ****

Ive tested out the 87 vs 89.. I get 1.5 - 2 more mpg with the 89.. which evens out over the extra $5 every time I fill the tank.

Sent from my SM-G920V using Tapatalk

Casper said:

89 is required on a stock truck. Why? Could it be because the PCV is vented into the intake manifold and the entrained oil vapor can cause pre-detonation and cause the PCM to pull timing?
Remember, Chrysler is not above cutting corners, and what they have done with the PCV is cutting corners. How do you fix that performance theft without costing Chrysler a dime? Simple, transfer the cost to the owner via higher gas costs by recommending 89.

Around where I live its $0.50 a gallon more for 89 compared to 87. Assuming a 30 gallon tank for easy math, that's $15 more a fill up, for maybe 2 MPG, or 60 additional miles.

My catch can paid for itself in eight fill-ups by keeping the oil out of my combustion chamber and letting me run 87.

I can more than break even buying 6 1/2 gallons more 87 at $2.30 a gallon. Its not like I'm running a street dragster after all.

Click to expand...

Aren't all PCVs vented into the intake?

Sent from my SM-G920V using Tapatalk

Oil vapor may contribute to detonation but that's not why 89 is recommended. It's 10.5 to 1 compression and hemi heads get into detonation easier than wedge style heads at the same compression. But it's your truck

I have run 87 since new, except for trips where only 89 or above was available. I haven't seen any real difference.

Rick Bobby said:

Oil vapor may contribute to detonation but that's not why 89 is recommended. It's 10.5 to 1 compression and hemi heads get into detonation easier than wedge style heads at the same compression. But it's your truck

Click to expand...

Which gets to my point, if entrained motor oil is causing the PCM to pull timing you would need better octane to offset the detonation. If you remove the oil vapor, good old 87 ought to be fine.
Its not like your running 15:1 compression and need AVGAS.

daveray9 said:

Aren't all PCVs vented into the intake?

Sent from my SM-G920V using Tapatalk

Click to expand...

Under smog control most are, but with the Hemi's higher compression and the common use today of shorter piston skirts and fewer piston rings, the Hemi produces a lot of blow-by compared to your typical six-banger, or engine with a flatter combustion chamber.
That blow-by winds up in the crankcase as oil vapor, some water vapor and combustion by-products including unburned fuel. The PCV uses vacuum from the intake manifold to suck all that nasty stuff out and then burn it off in the engine.

That stuff is no-bueno as fuel.

In addition to oiling up your intake over time it is of inconsistent composition introducing irregular combustion. Normal combustion is the burning (not "exploding") of a fuel and air mixture--it should burn in an even fashion across the chamber, with ignition originating at the spark plugs (2) and progressing across the chamber in a three dimensional fashion. Similar to a pebble in a pond, the flame front should progress in an orderly fashion. The burn moves all the way across the chamber and, quenches (cools) against the walls and the piston crown. The burn should be complete with no remaining fuel-air mixture. Detonation occurs when air and fuel that is ahead of the flame front ignites before the flame front arrives because the flame front is irregular. This combustion is uncontrolled and sporadic and can produce a pinging noise when the conditions become worse—except today you really can’t hear it in the cab through all the sound deadening materials.
Higher octane fuel burns more controllably and is less likely to combust before the flame front. Uneven combustion (detonation) occurs for a number of reasons, increased compression, high temperatures, lean fuel/air mixture, advanced ignition timing, and lower octane levels.
Entrained oil vapor from the PCV will lower the octane within the fuel air mixture while also effectively leaning your fuel mixture and preventing smooth flame front progression across the chamber.

Engine designers use test data to determine how much compression an engine can have and run at the optimum spark advance (objectively 14 degrees BTDC). The design compression ratio is adjusted to maximize efficiency/power using the anticipated fuel octane, and fuel air mix . Contamination from the PCV is anticipatable. Entrained oil and potentially water vapor can degrade combustion, leading to detonation. One of the most common adjustments to restore maximum performance without detonation is to retard the ignition timing, and that’s what the PCM does. Given the known introduction of combustion inhibitors by the PCV, the engine designers simply decided the way to ensure a stock engine would avoid detonation and achieve optimum timing for the Hemi's compression ratio was to specify a preference for a higher octane fuel.

A final option is the oil catch can which ensures the fuel air mixture is consistent, even with lower octane fuel, by preventing combustion interfering PCV dredge from entering the combustion chamber.

I admit, if I were so inclined, I wouldn't go stop light hustling with 87, but for around town, I get plenty of zip, and you only have to smell the nasty in the catch can to know that stuff is no-bueno for combustion.

Okay, got my catcher's gear on waiting for the spitballs from the catch can haters....!

Run 89 myself, I have a heavy foot so it makes me feel better .

I didn't know about the recommended 89 Octane, next fillup I will be switching to see the difference. Some members say not necessary if you have an OCC, True or false? Just installed the catch can this morning