RunsWithBeer
Active Member
The owners manual on 425 under technical specifications recommends 87 octane.
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Is it alright that I just put Premium fuel in my 2019 Ram 1500 Big Horn?
- Thread starter thabiiighomie
- Start date
For the 3.6L V6 engine, you are correct. For the 5.7, on page 426, its a different story.
RAM Patriot
Ram Guru
It is the BTUs that allows us to get the best fuel economy. Adding alcohol, of any kind, to gasoline, dilutes the fuel and lowers the heat energy.
The pumps provide us a choice of octane's. The higher the octane rating, the less chance there is of pre-ignition.
Octane has nothing to do with the BTU energy content of the gasoline, so use what your engine manufacturer recommends.
The pumps provide us a choice of octane's. The higher the octane rating, the less chance there is of pre-ignition.
Octane has nothing to do with the BTU energy content of the gasoline, so use what your engine manufacturer recommends.
So higher octane does allow for more timing and better HP/TQ...so it could be said someone does not use the gas pedal as much due to the higher performance.
Nominal at best I know.
RSConsulting
Well-Known Member
I love how these arguments rage on - akin to the "what kind of oil should I use?" (followed by lab results from oil that no one understands).
I todays computerized fuel/ignition systems - the computer will compensate for the entire range of octanes (and even go into "limp mode" for a bad batch of gasoline).
I run mid-grade, because that's what the manual says to run (and I run 5w20 - for the same reason - and my mechanic friend says stick with the recommended weight). Probably a waste of $$ - and I get pretty crappy mileage anyways. And if I wanted to get 20+ MPG, I wouldn't have bought a 7Klb Hemi V8 truck - likewise, if the mileage my truck got had me eating Raman Noodles - I'd be driving a Prius (rather sleep under a bridge in my truck - but I digress).
Back in the days of carburetors and timing lights - my Volkswagon Camper (yeah, I'm old) got 4MPG BETTER with 93, as opposed to 87. And I got comparable mileage and much better performance, when I ripped the fuel injection and electronic ignition out - and went with a Bosch 009 Distributor and Dual 43 ITC Webers.
I doubt anyone is going to see a "noticeable improvement" (seat-of-the-pants-dyno) running 93 over 89 (maybe, just maybe - 93 over 87) - and not likely the fuel mileage bump to justify the price bump (unless your CostCo is as cheep as 87 at a Shell station).
Running 93 isn't going to hurt your truck (as much as it hurts your WALLET). I've spent $4,772 on 87 - in 20,765 miles (2017 gallons - thank you fuelly app). At an average of $.30 more expensive for 93 - I would have spent $673 MORE on fuel. To get WHAT exactly? Certainly not better $673 worth of economy (or performance).
$673 buys a LOT OF RAMAN NOODLES.
YMM (obviously) V...
Rick
Edited to fix the typo - yes it's 5W20 - not 30...
As an added note - from the manual:
Fuel Selection – 5.7L Engines 89 Octane Recommended - 87 Octane Acceptable, 0-15%
Ethanol (Do not use E-85).
I todays computerized fuel/ignition systems - the computer will compensate for the entire range of octanes (and even go into "limp mode" for a bad batch of gasoline).
I run mid-grade, because that's what the manual says to run (and I run 5w20 - for the same reason - and my mechanic friend says stick with the recommended weight). Probably a waste of $$ - and I get pretty crappy mileage anyways. And if I wanted to get 20+ MPG, I wouldn't have bought a 7Klb Hemi V8 truck - likewise, if the mileage my truck got had me eating Raman Noodles - I'd be driving a Prius (rather sleep under a bridge in my truck - but I digress).
Back in the days of carburetors and timing lights - my Volkswagon Camper (yeah, I'm old) got 4MPG BETTER with 93, as opposed to 87. And I got comparable mileage and much better performance, when I ripped the fuel injection and electronic ignition out - and went with a Bosch 009 Distributor and Dual 43 ITC Webers.
I doubt anyone is going to see a "noticeable improvement" (seat-of-the-pants-dyno) running 93 over 89 (maybe, just maybe - 93 over 87) - and not likely the fuel mileage bump to justify the price bump (unless your CostCo is as cheep as 87 at a Shell station).
Running 93 isn't going to hurt your truck (as much as it hurts your WALLET). I've spent $4,772 on 87 - in 20,765 miles (2017 gallons - thank you fuelly app). At an average of $.30 more expensive for 93 - I would have spent $673 MORE on fuel. To get WHAT exactly? Certainly not better $673 worth of economy (or performance).
$673 buys a LOT OF RAMAN NOODLES.
YMM (obviously) V...
Rick
Edited to fix the typo - yes it's 5W20 - not 30...
As an added note - from the manual:
Fuel Selection – 5.7L Engines 89 Octane Recommended - 87 Octane Acceptable, 0-15%
Ethanol (Do not use E-85).
Last edited:
Scram1500
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I dont want to be that guy, but it's 5w20
RAM Patriot
Ram Guru
That has been my experience.
Not only do I not have to use the gas pedal as much but I find that the truck will go into ECO mode easier and stay in ECO mode for longer intervals than when I ran ethanol fuel and lower octane 87 gasoline.
JJRamTX
Ram Guru
I certainly won't hurt your truck to run 93, just your wallet!
RSConsulting
Well-Known Member
Typo - corrected... Thanks for the heads up - would hate to be misleading someone.
I agree other than the ethanol part. Even with ethanol the octane will be higher allowing for less pedal push and more eco mode...thus throwing the gas mileage reduction percentage a bit askew.
RAM Patriot
Ram Guru
Ethanol, Biodiesel, and Biomass
Brian F. Towler, in The Future of Energy, 2014
Fuel Economy of Ethanol
Pure ethanol has a high octane number (99), but an energy density that is 32.5% lower than gasoline (see Table 2.4). This means that adding ethanol in any proportion to regular gasoline will increase the octane number, but will lower the fuel economy. This might seem contradictory because most people believe that high octane fuels will give them a higher fuel economy (measured as miles per gallon). Octane rating, however, is not a measure of the energy content of the fuel, but instead is a measure of its ability to burn at high compression ratios without auto-igniting.
MarvsAMartian
Well-Known Member
Just adding my two pennies. I see a lot of 5.7 owners run only 87 in their trucks. I gave it a go and not only did my engine knock but the check engine light came on. Ran really really rough. Almost like I flooded the engine. Not sure if the 87 Octane gas in Canada is different but I burnt off half a tank, then filled it up with 91 and it eventually went away and runs normal now. I've been using premium since. I'm sure using 89 like the manual states will be fine but I'm paranoid about it now. My brother runs 87 on his 4th Gen 5.7 with no problems which is just overall confusing why mine did not take to it well.
RAM Patriot
Ram Guru
I had a little knock before I started running 89 octane. But with your check engine light coming on I think you might have got a bad tank of gas.
Keep in mind that Ethanol is also hygroscopic. If you go to a gas station that does not have good grading around the fill ups you could end up with water in the fuel.
That is why Marinas do not use ethanol fuel for boats.
MarvsAMartian
Well-Known Member
Thanks I didn't know that about marinas. I did chalk it up to bad gas as well but I just haven't looked back since going away from 87. Haven't put a drop of it in since that incident.
Again, I am not disputing this.
Just adding that the added ethanol to make the octane 89/91/93 could result in less gas pedal use/eco mode this throwing the numbers a bit askew.
RunsWithBeer
Active Member
Well, that sucks. Cost of ownership just went up appreciably.
RAM Patriot
Ram Guru
Blends of alcohols can be tested to determine what is called a “Blending Octane Value” or BOV. Basically, the octane rating of an alcohol/gasoline blend is compared to the octane rating of the gasoline without alcohol and some math is done to calculate what the effect of the alcohol was on the octane of the gasoline. Thus, a BOV is determined. However, a BOV is not the same thing as a normal octane rating.
Octane numbers at the pump are determined by taking the average of two ASTM-specified octane tests – the Research Octane Number test (RON, or simply “R”) and the Motor Octane Number test (MON, or simply “M”). The average is expressed as (R+M)/2 and is sometimes referred to as the Antiknock Index or AKI. In the United States, pump gas is sold based on AKI and it is this value that we typically use to represent a fuel’s octane rating. The square yellow octane stickers you see on gasoline dispensers indicate the (R+M)/2 octane rating.
BOVs for methanol and ethanol typically overstate octane. This is because the law of diminishing returns applies. While a little alcohol can bump octane by a few numbers, twice as much alcohol does not result in twice as much octane increase. So while it may look like an alcohol has a high octane number when a small amount is used (as in determining a BOV), its real octane value is not as high. Problem is, the real number can’t be determined… so we’re left to guessing.
JJRamTX
Ram Guru
The regular gas here in Colorado is 85 Octane and I only fill up at Costco or Shell because they have the best gasoline. I have never had any knocking or a check engine light running 85 for 90% of my 43K miles of fill ups and 87 for the other 10% while visiting other low altitude states.
MayhemMOORE
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I've run 89 since the day I got the truck, but still experienced audible pinging under moderate load/throttle in the 2700-3200 rpm range. Even since switching to 91, it's still there, and was extremely prevalent last week while towing about 5K lbs behind me. IMO, a modern vehicle should not ping as much this one does when using premium fuel. It also idles fairly rough and almost feels like it misfires while idling to the point I can actually feel it sitting in the driver's seat. I generally get fuel from the same station I have for the last 8 years unless I'm out of town, and never had issues with my Titan. I need to find time to bring it in to get looked at.
RAM Patriot
Ram Guru
If I was having that issue on my truck I would purchase a product like SeaFoam Motor Treatment to clean the injectors and intake valves and chamber deposits.
Ethanol based fuels are notorious for creating deposits and varnish deposits, due to the fact that ethanol is hygroscopic, as I had mentioned in the previous post.
