Another 87 vs 89 Octane Thread w/ My Results

[anmut]

I've been experimenting with running 89 octane over the last two months and finally have some results. They were surprising! Below is a good mix of city driving at 35mph avg, interstate at 78mph average, and local hwy at 63mph average.

Data was done by calculations vs. the onboard computer, however the onboard MPGs were spot on in my truck. Truck is a 2019 Limited with the standard 5.7 Hemi, 3.21 gears. I drive average, no hot rodding, but also not grandma like either.

89 octane @ $3.74/g
17mpg
Used 16.17 gallons
Drove 274.89 miles
Cost $59.65

87 octane at $3.34/g
15mpg
To drive 274.89 miles I would’ve used 18.32 gallons
Cost $61.82

Savings per fill up $1.56
Savings per 5k mile oil change $28.37

Boat towing season is just around the corner and I'll be following up with if my long distance towing of 6k lbs improves from 12.5mpg.

 

[aprez]

 

[theblet]

Looks like it worked out in your favor. Congrats. There are so many variables, idk if it would always work out that way. In my case 89 is like 50 cents more so I just do 87 unless I need to tow something heavy

 

[DEG]

You can't draw an accurate conclusion that it's the fuel giving you better mileage after driving less than 300 miles. You need to test for several thousand miles.

It's not uncommon for me to get 1 or 2 mpg better between tanks of the same fuel and similar city/highway driving. Things like wind direction and outside temperature differences can make a considerable difference. You can reduce those impacts by testing over multiple tanks of gas for several thousand miles.

I used 89 during a 3000+ mile road trip and the average was about 0.5 better than what I have since been recording over the last 4000 miles using 87. I attributed the 1/2 mpg improvement mostly to the higher % of highway miles than I normally drive, but even if it was entirely due to the 89 octane it wasn't enough to cover the additional cost of fuel. I noticed no increase in performance. The only thing I noticed was more money pouring out of my wallet.

 

[2021QCBH]

In the winter or flat lands I tow on 87. If it’s hot or I’m working it hard in the mountains it’ll get 89. All non towing = 87.

87 is presumably fine by the book but I can hear it detonate on mid throttle acceleration while towing so I bump it up.

 

[HSKR R/T]

I've been experimenting with running 89 octane over the last two months and finally have some results. They were surprising! Below is a good mix of city driving at 35mph avg, interstate at 78mph average, and local hwy at 63mph average.

Data was done by calculations vs. the onboard computer, however the onboard MPGs were spot on in my truck. Truck is a 2019 Limited with the standard 5.7 Hemi, 3.21 gears. I drive average, no hot rodding, but also not grandma like either.

89 octane @ $3.74/g
17mpg
Used 16.17 gallons
Drove 274.89 miles
Cost $59.65

87 octane at $3.34/g
15mpg
To drive 274.89 miles I would’ve used 18.32 gallons
Cost $61.82

Savings per fill up $1.56
Savings per 5k mile oil change $28.37

Boat towing season is just around the corner and I'll be following up with if my long distance towing of 6k lbs improves from 12.5mpg.

Need to get an average over at least three tanks of fuel on each octane, and preferably more. And not switching back and forth, but 3+ tanks of 89, get your average of the three tanks then three tanks of 87. Or vice versa. A one tank difference leaves a lot of variables in the table.

 

[anmut]

I'll keep documenting this over the next few months. Stay tuned.

 

[anmut]

You can't draw an accurate conclusion that it's the fuel giving you better mileage after driving less than 300 miles. You need to test for several thousand miles.

It's not uncommon for me to get 1 or 2 mpg better between tanks of the same fuel and similar city/highway driving. Things like wind direction and outside temperature differences can make a considerable difference. You can reduce those impacts by testing over multiple tanks of gas for several thousand miles.

I used 89 during a 3000+ mile road trip and the average was about 0.5 better than what I have since been recording over the last 4000 miles using 87. I attributed the 1/2 mpg improvement mostly to the higher % of highway miles than I normally drive, but even if it was entirely due to the 89 octane it wasn't enough to cover the additional cost of fuel. I noticed no increase in performance. The only thing I noticed was more money pouring out of my wallet.

As you can see from my original post, this has been over the last two months, approximately 2k miles. Yes, many variables to speak to of course, and I'll keep sharing as the temps change and the AC comes on.

 

[HSKR R/T]

As you can see from my original post, this has been over the last two months, approximately 2k miles. Yes, many variables to speak to of course, and I'll keep sharing as the temps change and the AC comes on.

Actually, the original post only showed just over 500 miles, total, being driven.

 

[anmut]

Actually, the original post only showed just over 500 miles, total, being driven.

2k miles on 89, the remainder wasn't tracked.