What fuel for 5.7

[Jared B]

I've heard good things about the black bear tunes for the GMs. I was thinking about doing a Jay Greene tune on my truck, you basically log your truck, send him the logs and he tunes for your specific trucks as well. Problem with the 2016+ FCA is that the PCM is encrypted and needs to be swapped to tune.

 

[alacombe]

Why is 89 recommended by the manual? Mopar getting kickbacks from oil companies I guess? . Most owners follow there manual to maintain warranty integrity. Anyhow I'm comfortable with following the recommended 89 octane. Ran it totally in the 2014 I traded on the 2019. I'm out!

You will not ruin the "warranty integrity" by running 87 octane. You do not need to run mid-grade gas.

 

[Twoamen]

In know that , my point is the manual makes a specific point that it is recommended.

 

[Jus Cruisin]

My truck was delivered with a full tank of 87. I've been putting in 89 and can't see/feel/hear any difference. Can't Teel if there is Amy mpg difference as I haven't done any hand calculations since my trip up to Michigan.

 

[alacombe]

My truck was delivered with a full tank of 87. I've been putting in 89 and can't see/feel/hear any difference. Can't Teel if there is Amy mpg difference as I haven't done any hand calculations since my trip up to Michigan.

I use 87 in my 2016 got 17mpg I am using 87 in my 2019 also. Your going to hear people say the manual says just 89 etc. Your not going to notice any difference.

 

[Jus Cruisin]

I use 87 in my 2016 got 17mpg I am using 87 in my 2019 also. Your going to hear people say the manual says just 89 etc. Your not going to notice any difference.

I'll likely go back to 87. I've got a couple of more weeks up in Michigan and finally heading back to Florida so by then I should have used most of the 89 and will pump 87 in it. I'll track my mpg for the trip back and compare the 2 trips. This one will be with a stop midway. Mother in law is heading south with us and I don't want subject her to sitting in the truck for 19 hours straight.

 

[Neurobit]

In know that , my point is the manual makes a specific point that it is recommended.

I follow the manual as well, so 89 for me. Since I've been running 93 for years on my prior vehicles, 89 feels like a steal...

 

[Edwards]

I follow the manual as well, so 89 for me. Since I've been running 93 for years on my prior vehicles, 89 feels like a steal...

I'm with you except they state "recommended" not "required". I'm going to do a test myself to see if 87 has any impact at all. If anything is different in the slightest I'll run 89 and consider it a discount. If not, then 87.

 

[Dkwatts1522]

I have ran both and can’t tell a difference in performance or milage. I fill up twice a week so I am thinking of sticking with 87 to save in my wallet since the manual say 87 is acceptable. FYI... I had an 04 VW Jetta 1.8T gas engine out of college and it recommend 92 or higher but when starting on cool/cold mornings it acted like an old Desiel. I took it to the dealer and was told to run 87 and it would take care of it. I ran 87 in that car for 13 years and it is still on the road with 190K miles. Started great on 87.

 

[19RamLimited]

I always use 93. I feel its worth it in the long run. I know the Ram is not Direct inject but I saw engines that ran 87 and they were filthy inside. carbon deposits really bad. I know 87 is ok but for the bit of money that it costs I like the 93. I run it in al my cars. It makes a huge difference in the long run and the performance is better all published numbers are higher octane numbers. The computers these days adjust to the lower octanes and run accordingly. They pull timing and thus horse power.

Its not noticeable until you drive a tank or two on the 93

 

[WRH]

Anyone do a reliable mileage test comparing the two?

 

[habu987]

I always use 93. I feel its worth it in the long run. I know the Ram is not Direct inject but I saw engines that ran 87 and they were filthy inside. carbon deposits really bad. I know 87 is ok but for the bit of money that it costs I like the 93. I run it in al my cars. It makes a huge difference in the long run and the performance is better all published numbers are higher octane numbers. The computers these days adjust to the lower octanes and run accordingly. They pull timing and thus horse power.

Its not noticeable until you drive a tank or two on the 93

I'd never run all 93 (or 91 around here), the economics don't work out in my particular situation especially with the ~$0.60 difference between 91 and 87), though they might for others. If we're talking about the midgrade the 2019s are rated at, it's still a ~$0.40 difference between 89 and 87.

I have my vehicles for an average of 3 years before I get a new one, whether I lease or purchase, and have historically put on 14-18k miles per year on them. If I were to get exactly the advertised combined fuel economy with 93/91/89 and 1 mpg less with 87, that's still a pretty big gap:

• 15k miles per year at, say, $3.40/gallon for 91 and 17mpg gives $3,000 for fuel expenses
• 15k miles per year at, say, $3.20/gallon for 89 and 17mpg gives $2,823 for fuel expenses
• 15k miles per year at, say, $2.80/gallon for 87 and 16mpg gives $2,625 for fuel expenses

Again, for me personally, I don't think an extra $375 in fuel costs per year is worth it, since that means I'd pay an extra $1,125 over the course of my normal 3 year period. If I were to tow or come close to using the truck's full capacities on a regular basis, that'd be a very different equation, but for my use case I don't think throwing an extra $1k+ at it is worth it.

 

[Willb]

Firat 2 tanks both ran to over 400 miles. I used 87 and averaged 18.5. 100 miles into my 3rd tank with 89 and I'm averaging 17.5. I drive basically the exact same roads since I live in the middle of nowhere. So for me performance is a wash and mpg isnt looking too good on 89

 

[Gman]

The biggest thing I've learned in my driving experience is that the quality of the fuel is likely more important than the octane in a non-turbo/supercharged engine (if you're following the mfr's guidance). I've had issues with rough idle and hesitation using gas that was bought on price and nothing else. I've had a much better motoring experience since I learned the difference between Top Tier Gas and the other stuff. I discovered that I have stations nearby that meet or exceed Top Tier standards at lower prices, including Sinclair and Costco.

https://www.toptiergas.com/licensed-brands/

The worst fuel that I was using was what I bought from Sam's Club.

 

[Tjd]

The CBC did a great story on the misgivings of using high octane fuel in vehicles that don't require it. In fact you could be doing damage by using it. Here is a link to the video https://www.cbc.ca/marketplace/episodes/2012-2013/pump-fiction

 

[MrHankbot]

Firat 2 tanks both ran to over 400 miles. I used 87 and averaged 18.5. 100 miles into my 3rd tank with 89 and I'm averaging 17.5. I drive basically the exact same roads since I live in the middle of nowhere. So for me performance is a wash and mpg isnt looking too good on 89

Is your 87 straight gas and 89 10% ethanol? That alone would explain the mpg loss.

 

[Gman]

Octane isn't about power. 87, 89, 93 have the same total quantity of energy per volume. Octane is all about stability. Higher octane is less likely to pre-ignite before the spark when it's heated under compression. The higher elevations where I live in CO are even less prone to pre-ignition due to the lower O2 per volume. We don't see really high Octane levels at our pumps because they are unnecessary.

...and as MrHankbot suggested above, alcohol contains less energy than gasoline per volume.

 

[MrHankbot]

Thank goodness, someone else who actually understands what octane rating really means.

 

[19blueram]

Just run what you think is best. Some people will say running 87 is best. Or 89 is best or 91 is best or whatever.
Colorado low grade is 85 Someone would think that’s to low. Modern engine computers adjust to what your running in the motor. Put in what you feel is the best for you. None of the octanes are wrong. It’s a personal choice but running what recommended in the manual is most logical choice but like it says it’s recommended not required.

 

[surfingcrna]

Octane isn't about power. 87, 89, 93 have the same total quantity of energy per volume. Octane is all about stability. Higher octane is less likely to pre-ignite before the spark when it's heated under compression. The higher elevations where I live in CO are even less prone to pre-ignition due to the lower O2 per volume. We don't see really high Octane levels at our pumps because they are unnecessary.

...and as MrHankbot suggested above, alcohol contains less energy than gasoline per volume.

Just wondering if the reverse is true, Do low altitudes require higher octane to maintain stability?