fuel

[gmpenn]

My dealer never told me this, found this on page 545 in the owners Manual
5.7L Engine
Do not use E-85 flex fuel or ethanol blends greater than 15% in this engine. This engine is designed to meet all emissions regulations and provide satisfactory fuel economy and performance when using high-quality unleaded gasoline having an octane range of 87 to 89 as specified by the (R+M)/2 method. The use of 89 octane “Plus” gasoline is recommended for optimum performance and fuel economy. While operating on gasoline with an octane number of 87, hearing a light knocking sound from the engine is not a cause for concern. However, if the engine is heard making a heavy knocking sound, see your dealer immediately. Use of gasoline with an octane number lower than 87 can cause engine failure and may void or not be covered by the New Vehicle Limited Warranty. Poor quality gasoline can cause problems such as hard starting, stalling, and hesitations. If you experience these symptoms, try another brand of gasoline before considering service for the vehicle.

 

[CrazyWorld]

My dealer...salesperson....said they only recommend 87 for the 5.7 hemi's. I also read what you posted....I asked the service department....the guy said he only runs 89 in his truck. I use 89 based on what you posted. Don't believe the dealers....they will say anything to sell a truck.

 

[Willwork4truck]

My dealer...salesperson....said they only recommend 87 for the 5.7 hemi's. I also read what you posted....I asked the service department....the guy said he only runs 89 in his truck. I use 89 based on what you posted. Don't believe the dealers....they will say anything to sell a truck.

Basically true. Over E-15 isn't good for your fuel system, it's not designed to be a Flex-Fuel truck. 85 is too low, 87 is "so-so", 89 is more optimum. Since not all areas/stations offer the mid grade, I usually run 87 and do hear a light ping.
I will use 89 if there's mts, large hills, or any real load potential. If you are on the flat and it's empty, 87 is fine.
I've seen "105" listed as the octane rating on the E-85 pumps...

 

[fflis]

Have you guys noticed a material difference in mpg running 89 octane. It’s like $.40 a gallon more here in Tampa right now. I was going to try it last tank, but then I was like hmmm for $9 extra, I’d have to get an extra like 50 miles out of each tank to make up the difference in cost. Didn’t seem worth it. I haven’t heard any knocking in my first 3 87 tanks.


Sent from my iPhone using Tapatalk

 

[Willwork4truck]

No increase in mpg's seen here (NC) between the 2. If you are in Fl with flat roads then by all means get 87 unless you are towing a bigger boat.

 

[Reverse]

Halleluja, someone actually read the manual

I use 87 all the time now. I do see a slightly higher mpg when on 89, but not enough to justify the price difference.

 

[Nails]

Have you guys noticed a material difference in mpg running 89 octane. It’s like $.40 a gallon more here in Tampa right now. I was going to try it last tank, but then I was like hmmm for $9 extra, I’d have to get an extra like 50 miles out of each tank to make up the difference in cost. Didn’t seem worth it. I haven’t heard any knocking in my first 3 87 tanks.


Sent from my iPhone using Tapatalk

Yes, I have noticed mileage gains from going up to 89 even 93.

 

[fflis]

Yes, I have noticed mileage gains from going up to 89 even 93.

Ya but enough to justify the increased cost? I’d guess not.


Sent from my iPhone using Tapatalk

 

[Jako]

I plan on keeping my Ram so I try to use top tier gas (primarily Costco) and blend the 87 and 93 octane to get 89. In my case it is difficult to determine the benefit of octane above 87 as my routine varies. However, I have done 400 mile trips using different octanes from 87 to 93. There are to many variables to reach a definite conclusion other than octane greater than 89 is a waste of money.
If you use 87 octane how much changes in performance?
If I was a short term owner I would follow the manual and use 87. I did not notice any difference with 87 but what is the long term consequences?
My brother's mechanic said he can tell what gas people use and 2 mechanics I know don't recommend 87. I still use 87 in my other vehicles as per manufacturer specs and they are fine.
There is a whole thing with port injection and direct injection, so perhaps depending on the motor design the quality and octane may play a bigger role if higher octane have more additives (top tier vs non top tier?) that keep the valves clean. I'm not a mechanic but started to educate myself when the Ford salesman told me to stick with the V8 if I was keeping the vehicle long term.
My Understanding of Octane:
Octane has to do with compression of the piston, low octane ignites with less compression than high octane. If the octane is too low the gas will ignite due to compression before spark. So 85 octane could/would ignite prior to spark (knocking pinging). If the motor is designed for 89 it should ignite with the spark. Adding more octane above 89 does not change the ignition of the gasoline as the 91 and 93 octane will ignite the same time as 89.

https://cars.usnews.com/cars-trucks/best-cars-blog/2016/08/premium-vs-regular-gasoline

Scotty Kilmer:

Interesting that as the motor is used there is carbon build up which could require higher octane later on. It is also my understanding that how you drive (light foot vs heavy foot) would have an impact so that a "conservative" driver may not have as much of an impact with low octane.
"Modern Marvels - Gasoline" if available is worth watching, also a history lesson.

 

[fflis]

I plan on keeping my Ram so I try to use top tier gas (primarily Costco) and blend the 87 and 93 octane to get 89. In my case it is difficult to determine the benefit of octane above 87 as my routine varies. However, I have done 400 mile trips using different octanes from 87 to 93. There are to many variables to reach a definite conclusion other than octane greater than 89 is a waste of money.
If you use 87 octane how much changes in performance?
If I was a short term owner I would follow the manual and use 87. I did not notice any difference with 87 but what is the long term consequences?
My brother's mechanic said he can tell what gas people use and 2 mechanics I know don't recommend 87. I still use 87 in my other vehicles as per manufacturer specs and they are fine.
There is a whole thing with port injection and direct injection, so perhaps depending on the motor design the quality and octane may play a bigger role if higher octane have more additives that keep the valves clean. I'm not a mechanic but started to educate myself when the Ford salesman told me to stick with the V8 if I was keeping the vehicle long term.

I’ve only had my truck long enough to fill up 3 times. I’ll probably try a mid grade here soon. It used to be that there was like a 10 cent difference between grades. I don’t really follow the price of gas, in fact I couldn’t tell you the last time I cared to look, but I was shocked to see how much more 89 octane was.


Sent from my iPhone using Tapatalk

 

[Willwork4truck]

Yep. 2 lousy octane points sure adds up a lot of cost. I occasionally blend the Costco 91 with my partial tank of 87 but not very often. While I don't much care for the soft pinging I hear on moderate acceleration using 87, it didn't seem to go away on 89 so ??? I wil still pay more when I expect to demand more from the truck as far as load, hills or if I am not using a top tier fuel.

 

[Nails]

For most probably not. I tried 93 over the summer as it’s super hot here. And added some pep & mpg back into the truck. So I’ve just kept with it.

 

[GasTank87]

Theres a guy on one of the Facebook 5th gen pages who is running data logs and the 5.7 definitely doesnt like 87. It was pulling as much as 5 degrees of timing while running that. Hes slowly working his way through the fuel grades and running logs on each. Itll be interesting to see his results on 89.

Sent from my SM-G973U using Tapatalk

 

[Nails]

^^^ nice, it’s been shown hemis have super sensitive on knock. Constantly pulls timing

 

[fflis]

Theres a guy on one of the Facebook 5th gen pages who is running data logs and the 5.7 definitely doesnt like 87. It was pulling as much as 5 degrees of timing while running that. Hes slowly working his way through the fuel grades and running logs on each. Itll be interesting to see his results on 89.

Sent from my SM-G973U using Tapatalk

There’s a handful of different fb groups. Got a link?


Sent from my iPhone using Tapatalk

 

[GasTank87]

There’s a handful of different fb groups. Got a link?


Sent from my iPhone using Tapatalk

It's just called 5th Gen Rams. Might have to scroll down the page a little bit. It was posted yesterday the 7th.

Log into Facebook

Log into Facebook to start sharing and connecting with your friends, family, and people you know.

www.facebook.com

Sent from my SM-G973U using Tapatalk

 

[GasTank87]

^^^ nice, it’s been shown hemis have super sensitive on knock. Constantly pulls timing

Yeah he said it was pulling that much time just at cruising speed. Up to 8 degrees under heavy load. He updated and said it was still pulling a little timing on 89 under load but not as much, however it wasnt pulling any timing under cruising conditions.

Sent from my SM-G973U using Tapatalk

 

[Jako]

Theres a guy on one of the Facebook 5th gen pages who is running data logs and the 5.7 definitely doesnt like 87. It was pulling as much as 5 degrees of timing while running that. Hes slowly working his way through the fuel grades and running logs on each. Itll be interesting to see his results on 89.

Sent from my SM-G973U using Tapatalk

I assume the 5 degrees is the adjustment for the 87 octane which reduces performance. How much less performance and does this have an impact on the engine longevity?

 

[GasTank87]

I assume the 5 degrees is the adjustment for the 87 octane which reduces performance. How much less performance and does this have an impact on the engine longevity?

I dont think I'd worry about longevity since the knock sensors and computer is doing exactly what it should to make sure theres no/very minimal knock. But, if you're retarding timing, then yeah, performance and fuel economy will have to suffer. Now by how much? I dont know. Maybe its negligible. I couldnt say.

Sent from my SM-G973U using Tapatalk

 

[ForTehNguyen]

i ran two tanks of regular 87 to compare when I first bought it. Truck felt sluggish, trying to maintain mpg on freeway was finicky and a chore. Ran a lot smoother on midgrade 89