HO fuel requirement

[ericbsc]

Just traded for a 2025 longhorn limited. I knew the fuel said 91 octane. Why ? What would it hurt to run mid grade?

 

[Farmer Fran]

91+ required could be a few factors, but I will only run 93 in mine

 

[turkeybird56]

Just traded for a 2025 longhorn limited. I knew the fuel said 91 octane. Why ? What would it hurt to run mid grade?

The motor has several different internals than the lower SST. Motor tuned to run 91 +++

 

[Dean2]

You bought an HO for more power. Part of how more power is made is running higher octane fuel. If you want to run it on cheaper fuel that is your choice but it isn't optimal. I have high performance V8s in a couple of cars. The high compression, naturally aspirated motors want premium gas. It is what I feed them as I knew about the requirement when I bought them. Regular to premium here is about 45 cents a gallon more for the extra octane.

 

[Docwagon1776]

It won't hurt anything mechanically, as the computer won't let you and will pull timing. Lower octane fuel will detonate earlier, though, so the motor will pull timing sooner to avoid knock. Pulling timing means less power, worse fuel economy, and more heat.

The Hurricane HO already makes more heat than it can shed under heavy load, which is why the tow rating is lower than the SO. Once heat builds up, timing has to be pulled even further, starting a loop of needing more fuel to create the same level of power creating more heat pulling more timing.

So, if you're just puttering around town, maybe slightly worse fuel economy at a level you're unlikely to notice. If you actually use it, you're making the timing spiral occur earlier.

 

[Wild one]

You might want to check into your warrenty,as it might disappear if they can prove you didn't run the required fuel.
The SRT 6.4's call for 91 because of the higher cylinder pressures they have,and according to my local dealer if you have a engine warrenty claim,and Ma Mopar thinks you didn't run the proper fuel,they'll deny the warrenty claim.
These days Stellantis looks for any way they can to deny a warrenty claim,so is it worth it to save a few bucks on the fill up

 

[Docwagon1776]

You might want to check into your warrenty,as it might disappear if they can prove you didn't run the required fuel.

This is also true. The owner's manual specifically warns you of this.

In reality, I think you'd have to be pushing the motor pretty hard for it not to be able to deal with 89, but if your dealership wants to make an issue of it you're giving them the excuse to try.

 

[LOWRMPG]

Run premium, the truck cost over 70,000+ my guess is a buyer can afford a few extra dollars on gas. IMHO, it isn't worth the risk of one of the numerous sensor crapping out because an owner chooses not to follow the requirement. As was stated, you're giving a dealer a reason to make any issue your problem. The total savings if you filled up 33 gallons would be between 9-16 dollars, seriously doesn't seem worth it.

 

[Dean2]

Run premium, the truck cost over 70,000+ my guess is a buyer can afford a few extra dollars on gas. IMHO, it isn't worth the risk of one of the numerous sensor crapping out because an owner chooses not to follow the requirement. As was stated, you're giving a dealer a reason to make any issue your problem. The total savings if you filled up 33 gallons would be between 9-16 dollars, seriously doesn't seem worth it.

I agree but guys should not trivialze the extra cost of having to run premium. If that is his daily driver, that is 800 to a 1000 bucks a year, 4-5000 bucks over 5 years. Guy should factor in running costs when choosing a daily driver. If the extra grand a year is no big deal, good. If it is. Might be should choose a different vehicle or engine option.

 

[Farmer Fran]

3.0L HIGH OUTPUT ENGINE — RHO Do not use E-85 flex fuel or ethanol blends greater than 15% in this engine. This engine is designed to meet all emission regulations, provide optimal fuel economy and performance when using high-quality unleaded premium gasoline having a posted octane number of 91 as specified by the (R+M)/2 method. The use of 91 or higher octane premium gasoline is required in this engine.

Page 412 2025 Owners manual - You would be freaking nuts not to put that fuel in an $80,000 truck. Be it the lack of knock sensors, the boost, whatever it is. They have zero reason the REQUIRE 91+ other than damage.

 

[Docwagon1776]

They have zero reason the REQUIRE 91+ other than damage.

Well, not quite zero. A vehicle designed for a given octane will also have higher emissions and lower mpg if using a lower octane as the motor pulls timing and can't use as much boost. Damage is certainly the more costly concern, but it's not the only motivator for an OEM to mandate use of a given octane.

 

[Farmer Fran]

I am willing to bet it is in the timing charts and the detonation will happen too fast for the sensors in the HO, can you go 150K miles problem free? maybe

But I will not even attempt it.

 

[White six four]

Regular to premium here is about 45 cents a gallon more for the extra octane.

The total savings if you filled up 33 gallons would be between 9-16 dollars, seriously doesn't seem worth it.

I wish premium around me was as close to regular as you guys. Premium, 91 octane, is always 80 cents to a buck more per gallon then regular 87. I still use premium in my truck, just because it doesn't have ethanol. It's not my daily so it sits a lot.

 

[Mlarv5]

I had a 2013 Shelby GT500 it required 93+ octane. I had to buy the 93 octane, and the car ran great MPG was up there. I was running low on gas and the best I could get was 91 octane. I could not get any boost and the engine ran like crap.

If the MFG says 87 octane is required or better I will run 87 until I need to tow, then I will fill with 93 until I am done towing. If they say 91 octane like in the above case I would run 91+. The engine runs cooler will pull better and not work as hard.

I put flex fuel in a 3.6 penstar 2014 Jeep JKU. I had to run it to half a tank fill it with 93 a few time before that crap was out of the tank.

If the MFG says run XX+ or better then I run it.

 

[Docwagon1776]

I am willing to bet it is in the timing charts and the detonation will happen too fast for the sensors in the HO, can you go 150K miles problem free? maybe

But I will not even attempt it.

I don't know it'll go 150k miles on unicorn tears and 99 octane super premium extra v irgin organic gasoline, but the chief engineer for the Ram 1500 (Doug Killian) has publicly stated 87 octane won't damage the motor.

I'd be more concerned about heat downstream and emissions components than the motor not pulling timing fast enough, but I'm not buying one so it's pretty hypothetical to me. I'll stick with my dumb ol' naturally aspirated 6.4L.

 

[Wild one]

You bought an HO for more power. Part of how more power is made is running higher octane fuel. If you want to run it on cheaper fuel that is your choice but it isn't optimal. I have high performance V8s in a couple of cars. The high compression, naturally aspirated motors want premium gas. It is what I feed them as I knew about the requirement when I bought them. Regular to premium here is about 45 cents a gallon more for the extra octane.

I think you mean 45 cents more per litre not a gallon,lol.
If you're getting 91 for only $0.45 more a gallon then 87,i want to know where,lol

 

[Dean2]

I think you mean 45 cents more per litre not a gallon,lol.
If you're getting 91 for only $0.45 more a gallon then 87,i want to know where,lol

Costco. 135 for reg, 155 for premium. 20 cents time 3.8 is actually 76 a U.S. gallon but up until recently premium was only 15 cents more a litre so 57 cents a gallon. I just did the math, I was ballparking it earlier.

 

[Wild one]

Costco. 135 for reg, 155 for premium. 20 cents time 3.8 is actually 76 a U.S. gallon but up until recently premium was only 15 cents more a litre so 57 cents a gallon. I just did the math, I was ballparking it earlier.

I've never bought fuel at costco,as it's a fair ways out of my way,and i don't have a membership card,but that's good to know

 

[Farmer Fran]

I don't know it'll go 150k miles on unicorn tears and 99 octane super premium extra v irgin organic gasoline, but the chief engineer for the Ram 1500 (Doug Killian) has publicly stated 87 octane won't damage the motor.

I'd be more concerned about heat downstream and emissions components than the motor not pulling timing fast enough, but I'm not buying one so it's pretty hypothetical to me. I'll stick with my dumb ol' naturally aspirated 6.4L.

Would love a link to that post/comment/video

 

[Docwagon1776]

Would love a link to that post/comment/video

The 2025 Ram 1500 Hurricane HO: Premium Fuel Optional

The new 2025 Ram 1500 is available with a high-output inline six-cylinder engine that maxes out with premium fuel. But you don't need it.

www.edmunds.com

"from Ram 1500 chief engineer Doug Killian, even though it's recommended, it’s not a requirement."

""The high-output Hurricane performs better with premium gasoline,” Killian explains. “But if you use regular 87 octane fuel, it would only be slightly noticeable to the person really maxing out that engine.”"

"Knock sensors will detect any abnormal vibrations, keeping the truck on track to adapt to lower-octane fuel as necessary. If the operator eschews premium fuel, the truck won’t be able to hit its peak power numbers, but that may not be a main concern for many drivers. For instance, if you’re driving a Ram 1500 back and forth to work or hauling light loads, you probably don’t need to shell out for the good stuff. Those who operate in a hot environment with a heavy load — think towing a heavy trailer mid-summer in Phoenix — will find that premium fuel provides the most optimal performance."

"“The engine is really going to operate at its potential with premium fuel,” Killian says. “But it [will have] no problem running, and the typical driver will certainly find very good performance on regular 87 octane fuel.""