What fuel for 5.7

[Jamo237]

...or don't. I really don't need to put that much thought into it. The truck runs great on Mid-grade. I don't notice any real difference running Premium. If I can get Premium at the Mid-grade price at Costco (and don't even have a Mid option), then I'll get that.

@Jamo237 - Which Mercedes are you coming from? I sold my 2016 GL 450 and got into my Limited as my first pickup/first FCA product. I only used Premium in that bi-turbo, but it really needed it. I'm happy to add more gallons of Mid-grade for the same cost as fewer gallons of Premium.

2018 GLC. Gas mileage never impressed me. I traded it in yearly and bought the new model. Had a kid and needed more space. Haven’t regretted going with the limited. Love the truck and wish I did it sooner. Funny how some people are shocked I left Mercedes yet my truck was more expensive than the Benz.
No regrets at all.
Ran 93 for two tanks since my last post. Actually got slightly worse gas mileage for whatever reason. Put 89 back in yesterday and did my same daily trip last two days and my mileage is up slightly. Think I’m going to stick to 89.
On thruway I’m getting 21mpg. City is about 14-15 with me taking it easy.

 

[tmartley]

Can someone tell me what octane is recommended for the 5.7?
Thanks

my 2019 LMITED 5.7 V8 runs best on 89 as recommended by book. However, I do have the Etorque system and maybe that makes a difference.. I am experiencing about 2 mpg more with 89 over 87

 

[Jus Cruisin]

I've been using 89 when I'm working the truck hard. Otherwise I'm using 87 without any issues. I know I'm losing some performance but for just tooling around I'm good with it.

 

[kevinssaco]

I noticed a slight difference between a good Shell/Mobil/Exxon tier 1 87 and 89. Usually at low speeds and colder weather. 89 ran a bit smoother with MDS kicking in and out. I just find the cost difference too great to put it in the tank.

 

[KcRay]

I noticed a slight difference between a good Shell/Mobil/Exxon tier 1 87 and 89. Usually at low speeds and colder weather. 89 ran a bit smoother with MDS kicking in and out. I just find the cost difference too great to put it in the tank.

Been running 87 all its life, (6k miles) just put in first tank of 89, am about half way through this tank. Don't notice any difference yet. Will run a couple of tanks to check the milage, I get around 16.5-17.0 mpg with 87.

 

[TheMadDutchDude]

I use 93 in my truck, have done since it came off the lot back in Feb.

Personal preference, I guess. I do like to rag my motor a bit when she’s warm, so I prefer to have the better fuel in there.

 

[KcRay]

I use 93 in my truck, have done since it came off the lot back in Feb.

Personal preference, I guess. I do like to rag my motor a bit when she’s warm, so I prefer to have the better fuel in there.

What kind of mpg are you seeing with 93? I like to use that pedal on the right as well.

 

[silver billet]

I use 93 in my truck, have done since it came off the lot back in Feb.

Personal preference, I guess. I do like to rag my motor a bit when she’s warm, so I prefer to have the better fuel in there.

This is a common missconception. A higher number does not equal "Better fuel". The best fuel to run, is the fuel your engine was designed to run at. If it needs 87 octane, run 87, if it needs 94, run 94; the hemi needs 89, so run 89.

We're conditioned to think "higher or more = better", but that is simply untrue when it comes to octane.

A relevant quote from this link: http://www.whatcouldbegreener.com/142/fuel-octane-choosing-the-wrong-octane-will-cost-you/

What will happen if I use higher octane gas than I’m supposed to?

A few things. For one, you will be wasting a huge amount of money paying for high octane gasoline. Second, your car will not run correctly, whether you notice it or not. Higher octane fuel requires more heat and more precision to burn correctly. If your car is designed to burn 87, it will not burn 93 correctly. Third, your gas mileage will suffer. The inability of your engine to burn the higher octane gas correctly will cause your engine to produce less power and thus will require more fuel to perform at the same level.

 

[TheMadDutchDude]

Well, when I used to get gas at Costco, it was 87 or 93. I opted for the higher octane and have done ever since. My engine has been running on it since day one. However, I may drop to 89 seeing as I haven’t been near Costco after my job switch.

There’s no harm in using higher octane fuel. It will just cost more to run. Running on lower octane, however, isn’t that great, but the knock sensors will adjust accordingly.

Everyone has different theories and methods, so I’m not sure if there’s a 100% correct answer. I’m a newbie, though, so I am expecting to be corrected.

As far as mileage goes, I am used to getting between 16 and 17 city and 22 highway, but I am always at ... “more” than the speed limit.

 

[silver billet]

There’s no harm in using higher octane fuel. It will just cost more to run.

I'm not a chemist nor an engine engineer; but again, please read this relevant quote in bold :

Higher octane fuel requires more heat and more precision to burn correctly. If your car is designed to burn 87, it will not burn 93 correctly.

To me that sounds harmful.

Putting in higher octane gas just because you feel the higher octane is better, is like putting in 10w-40 oil in when the manufacturer says "put in 5w-10" just because the numbers are higher.

Your engine is designed around certain parameters; going outside those parameters is not a good idea when you don't know 100% what they do.

 

[_StangPGH]

Exxon, Shell, etc also reserve their higher end additives for higher octane fuel. Whether those detergents, etc are worth the added benefit of a cleaner engine over the life of a vehicle or if they're even doing anything at all is hard to prove out.

Sent from my SM-G950U using Tapatalk

 

[cra1g]

I'm not a chemist nor an engine engineer; but again, please read this relevant quote in bold :

Higher octane fuel requires more heat and more precision to burn correctly. If your car is designed to burn 87, it will not burn 93 correctly.

To me that sounds harmful.

Putting in higher octane gas just because you feel the higher octane is better, is like putting in 10w-40 oil in when the manufacturer says "put in 5w-10" just because the numbers are higher.

Your engine is designed around certain parameters; going outside those parameters is not a good idea when you don't know 100% what they do.

Not sure I'd put any stock in some random sciency-sounding blog post.

From what I've read, the harm from higher octane can happen when you're WAY over what your engine requires (like 114 octane race gas). Under certain conditions, the higher-octane fuel won't burn fast enough, and can start leaving deposits on your exhaust valves. I don't believe 93 will hurt anything in an engine designed for 89, but it won't help anything either, so it's just a waste of money.

 

[silver billet]

Not sure I'd put any stock in some random sciency-sounding blog post.

From what I've read, the harm from higher octane can happen when you're WAY over what your engine requires (like 114 octane race gas). Under certain conditions, the higher-octane fuel won't burn fast enough, and can start leaving deposits on your exhaust valves. I don't believe 93 will hurt anything in an engine designed for 89, but it won't help anything either, so it's just a waste of money.

I believe the "dirty engine" is what happened to one of my cars (94 pontiac) when I was putting in ultra 94 for a year. Ended up dumping in some cleaner into the fuel and going back to 87 and it ran better the rest of the time I owned it.

The manual states "for optimum power and efficiency run 89". It doesn't say anything about performance or other gains beyond the 89. To be fair I guess, it also doesn't say "running 93 will harm your engine in the long term", but it just isn't worth the risk IMO.

 

[Gman]

There's really no 'risk' to the engine going with Premium fuel. It's just not necessary and can be dollars burned that could be spent elsewhere.

I fueled up with Top Tier Sinclair Mid-grade on Wed. evening. I headed out to Moab, UT Thursday morning with 2 passengers and a bunch of gear. Got 23.1 mpg on the trip out. We were staying at a cabin at about 7400 feet in elevation. Drove a bunch of dirt roads in 4WD/Offroad 1 down to town at about 4,000 ft. and up to Warner Lake Campground up around 9400 ft., tooled through Arches National Park at 106 degrees, idled the truck for about 2 hours with the AC running, drove out to Dead Horse Point to watch the sunset last night, and drove back today. Topped off with Mid-grade in Moab and still have 1/2 tank left. Spent 30 minutes crawling up to the Eisenhower Tunnel (metered lanes to slow traffic). Stop and go for a chunk of the drive from there back to Denver. Averaged 21.9 mpg for the entire 4-day vacation.

I'm so impressed with this truck. I'm at about 6500 miles on it and it just keeps getting better. The best I could get out of the Mercedes GL 450 3.0l bi-turbo on the highway was 21 mpg.

Now to get all of the dust out of every nook and cranny.

ETA: I ran across this article tonight: Should You Be Buying Premium? Honda CR-V, BMW M5, Ford F-150, Dodge Charger Tested

Dodge Charger R/T
We always assumed that mid-grade fuel existed chiefly to bilk a few more dimes from the type of person who asks the dealer to undercoat his car. Turns out it's also for owners of Fiat Chrysler's Hemi 5.7-liter V-8, as the company recommends 89-octane fuel for this engine. With no mention of that on the fuel-filler door, though, a driver would have to read the manual to know. And we don't see that happening in the case of this particular Charger R/T, which was cherry-picked from the Detroit airport rental lot for our test. With just 600 miles on the odometer and looking as if it had already been hand washed with 80-grit sandpaper a half-dozen times, this Charger is unlikely to ever taste 93 octane again.

Oh well. The Charger's manual says 87 octane will provide "satisfactory fuel economy and performance." In our testing, "satisfactory" proved to be nearly identical to how the car performed with premium gas. Similar to the BMW, the Dodge's gains on the dyno (14 horsepower and 23 pound-feet of torque) translated into negligible improvement in our real-world acceleration testing. Saddled with elephantine heft and eager to spin its rear all-season tires at launch, the Charger posted the same 4.9-second hustle to 60 mph on 87 and 93 octane. At triple-digit speeds, the higher power on 93 octane gave the Charger an advantage measured in tenths of a second. The Dodge also posted a 0.3-mpg improvement on premium with its average of 23.5 mpg. Just as important, the bellicose roar of the iron-block Hemi and the Charger's ability to reduce its rear tires to jungle-gym ground cover are unaffected by the fuel in the tank.

While Ford's EcoBoost F-150 stands out as an obvious exception, the Dodge Charger's numbers make for a tidy summary of our findings. If you buy fuel with an octane rating above the manufacturer's requirement, you're likely to feel it in your wallet more than the seat of your pants.

Would have been interesting if they actually tested the recommended 89 octane.

 

[SD Rebel]

I'm not a chemist nor an engine engineer; but again, please read this relevant quote in bold :

Higher octane fuel requires more heat and more precision to burn correctly. If your car is designed to burn 87, it will not burn 93 correctly.

To me that sounds harmful.

Putting in higher octane gas just because you feel the higher octane is better, is like putting in 10w-40 oil in when the manufacturer says "put in 5w-10" just because the numbers are higher.

Your engine is designed around certain parameters; going outside those parameters is not a good idea when you don't know 100% what they do.

First, that article is from a blog, I don't see any scientific notations to actually backup what appears to be an opinion piece by the author. Though can't tell, since even the person who wrote it isn't sited either.

From what I seen in testing, fuel at the pump are usually 1-2 points higher than advertised to make sure they are at least getting the minimum octane rating.

I haven't found any info online that states you will hurt performance if you use 91/93 instead of 89. In most situations, you are getting a higher octane that stated anyways just by industry practice. That 89 you are pumping is likely closer to 90 or 91, especially since it's a blender system that mixes 87 and 91/93 that already 1 point above the stated octane.

 

[TheMadDutchDude]

I just remembered why I went with 93 instead of 89 ... I used to fill at Costco where 93 was the price of 87 everywhere else. Now I no longer work out that way, I have to fill at a Shell or similar, making 89 much cheaper and the fuel I currently use.

I noticed a weird fuel cut (assuming, it hiccuped for a split second at the higher revs) the first time I put 89 in going from 93, but have since taken her to 5500 revs a few times with no issue. Maybe it just needed a slight readjustment or something.

 

[Gozar]

I can get "No ethanol" gas near my house.
Good idea, bad idea? I usually run 87 from Costco with the occasional tank of 89 from Shell ($.05 off for being a Gold Member still helps).

Thanks

 

[Gman]

It all depends on what you pay for it vs. what you get out of it. Gasoline contains more energy per volume than ethanol, so you may get more mpg. If there's no difference in cost, I'd go with the straight version, as long as it was from a Top Tier supplier.

 

[devildodge]

Found out my local Rutters only has a 20 cent difference between 87 and 89. Got 3 tanks of 89 run through. No noticable difference. Will run 89 for the time being. Won't be towing for another weekend, but then 2 in a row. My "highway" driving has been right at 16 and my daily has been right at 13. My towing between 8.5 and 11.

Perfectly okay with that as my 99 V10 averaged 10mpg daily. It could get 16, but not regularly and was usually about 8 to 9 towing.

I believe I will pass on the 90 non ethanol. Almost a buck more...say on avg. Between 55 and 85 cents...and I got worse mileage and similar if not actually worse performance. Not impressed.

I bought this Heavy Duty for the 8 foot bed and 410 horses to drag it around...perfectly content with giving it 32 gallons to drink.

 

[Monteman1971]

I've always learned and know that using a higher octane than what the engine requires is a waste of money......with that said I've owned an 05, 08, 11, 14, 17 and now a 2019 Ram and each time it was recommended to run 89 octane and stated that 87 was fine. I did multiple comparison tanks on all these trucks (except the 19 as of now) running 87 octane vs 89 octane and found no difference in "seat of the pants performance" or manually calculated gas mileage. So I've run 87 in all of them. I try to use the 89 if towing (approx 7500lbs, car and trailer) but if I forget and use 87 octane I still have never experienced any pre-detonation or apparent performance issues.

My 2 cents
Steve