Using 89 octane for first time.

MR.Z06 · Jun 10, 2016

MANual_puller said:
Depends on how you look at it. He's likely getting worse MPG with the 87 right now than he would be getting with the 89. I normally pick up 1.5ish average for the summer months and that seems to be fairly constant no matter what octane rating people run. Idk if giving up that gain is worth it. I run 91 octane because I didn't like what I was seeing watching knock retard numbers with 89 octane. It wasn't bad, it would pull about 4 degrees in the mid RPMs at WOT and up to 7 in the high RPM ranges. The better fuel made it all but go away. DSP recommends running 89 or higher with all their tunes. I would set it back to stock and see what the factory tune does with the 91 octane but then I'll have to write down my shift schedule....yada yada yada, I'm not really that curious since my truck is much happier than it was.

I bought the 'lifetime' warranty so I am religiously following the owners manual. 89 oct, for me period.
I would love love love to get a tune but I SWEAR that this truck will be the first vehicle that I don't void the factory warranty within the first 1000 miles.

GP4L · Jun 10, 2016

[/IMG]

About 25% into my last long highway trip - taken after I stopped for food.
89 octane from Mobil - I remember because that particular station by my house has a touchless car wash that I used before my trip. Tire pressure was 43-44psi hot - OEM GY tires on OEM 20's - fresh engine oil, new air filter. Soft bed cover. Everything else is stock. Truck configuration listed in my sig.

That's the type of mileage I always see on highway trips. I've seen as high as 23 average, low as 20. But usually 21-22. EVIC is usually at worst +- 0.2 of my calculator when I tank up. Every time. Yes I have a little OCD. Lol.

Not sure how it's contributing to this thread, but :biggun:

Graygoose · Jun 10, 2016

Amazes me some look for performance 'gains' on parts yet cheap out and use mouse ***** for gas.
I've always used 89 in both my trucks. There are variances in companies, and in octane ratings. Don't let a few bucks up at fill discourage you.

MR.Z06 · Jun 10, 2016

Graygoose said:
Amazes me some look for performance 'gains' on parts yet cheap out and use mouse ***** for gas.
I've always used 89 in both my trucks. There are variances in companies, and in octane ratings. Don't let a few bucks up at fill discourage you.

Well this truck is by far the most fuel efficient vehicle I own, so that should tell you something about how much MPG influences my vehicle choice.
However.
The differences in fuel costs can become quite significant, of course dependent on how long and how many miles driven, but many thousands of dollars significant over the life time of the vehicle.
I mean I can understand how it could be an issue for a lot of folks. Especially the small business guys.

Graygoose · Jun 10, 2016

Well fuel cost need to be determined at time of purchase. If a truck, with a huge savings on gas, maybe a Hemi isn't the answer. But a Toyota, or small engine truck. But for $9.00 at a fillup, I'll take all the power my truck provides already.

MANual_puller · Jun 10, 2016

MR.Z06 said:
I bought the 'lifetime' warranty so I am religiously following the owners manual. 89 oct, for me period.
I would love love love to get a tune but I SWEAR that this truck will be the first vehicle that I don't void the factory warranty within the first 1000 miles.

We don't worry about warranty. I've never owned a vehicle with warranty and I don't intend to. I didn't put the first 92k miles on this truck, I'm at 101k now so the warranty is long gone :happy107:

Graygoose · Jun 10, 2016

Kotta390 · Jun 10, 2016

MR.Z06 said:
Most people have no clue what an oct rating is or what it means.

Exactly!! I love it when people refer to higher octane fuels being a much cleaner fuel to use than the regular 87 octane! :roflsquared:

Booms · Jun 10, 2016

Octane boost ftw !!

THETANK · Jun 10, 2016

GP4L said:
[/IMG]

About 25% into my last long highway trip - taken after I stopped for food.
89 octane from Mobil - I remember because that particular station by my house has a touchless car wash that I used before my trip. Tire pressure was 43-44psi hot - OEM GY tires on OEM 20's - fresh engine oil, new air filter. Soft bed cover. Everything else is stock. Truck configuration listed in my sig.

That's the type of mileage I always see on highway trips. I've seen as high as 23 average, low as 20. But usually 21-22. EVIC is usually at worst +- 0.2 of my calculator when I tank up. Every time. Yes I have a little OCD. Lol.

Not sure how it's contributing to this thread, but :big gun:

not bad numbers, I just finished a trip that one way was 10 X's longer + 200 miles and was happy to see 25.6 mpg @ 60 mph average. :happy107:

noupf · Jun 11, 2016

just came back from one of my controlled trips. This time, as one of the posters mentioned, summer driving ( maybe he meant summer blend ), should have yielded an increase ( usually around 1.5 mpg increase is the general consensus online ).

Well, i filled up with 89 from almost empty and took my journey... this trip yielded 19.4 mpgs......which was barely on the higher side of my results from a few months ago when i was running 89 octane on the same controlled trips.

Stay tuned, i am doing the exact same trip tomorrow night as well.

RLJ10X · Jun 11, 2016

Locally, Marathon is th gas to beat as far as mpgs. There are several of my friends and I believe the local Sunoco distributorship waters down their gas. I've had good luck with BP, also.

Kytow · Jun 11, 2016

BP and Shell are what I try to stay with. Have to use Valero at times. Filled up with Sunoco yesterday.

Sent from my iPhone using Tapatalk

MANual_puller · Jun 11, 2016

noupf said:
just came back from one of my controlled trips. This time, as one of the posters mentioned, summer driving ( maybe he meant summer blend ), should have yielded an increase ( usually around 1.5 mpg increase is the general consensus online ).

Well, i filled up with 89 from almost empty and took my journey... this trip yielded 19.4 mpgs......which was barely on the higher side of my results from a few months ago when i was running 89 octane on the same controlled trips.

Stay tuned, i am doing the exact same trip tomorrow night as well.

I'm not 100% convinced there's any difference in gasoline between summer and winter. Warmer air, as indicated to the PCM via the IAT sensor, is less dense. The engine needs a constant A/F ratio so it will put less fuel into warmer air, thus helping fuel economy. Likewise that same warmer air that is less dense has less aerodynamic drag on the truck while driving, also helping fuel economy. I'm pretty certain this is why the same octane rating yields better fuel economy during the summer months.

Octane ratings are just that, energy/volume. The PCM will respond to fuel with lower octane in 2 ways, pulling timing initially as a response to detected knock to avoid detonation, and adding fuel as a response to oxygen levels in the exhaust as detected by the upstream O2 sensors. When you plug in a tuner and watch for knock retard you can monitor the quality of the fuel. If it's not retarding, it's likely not dumping extra fuel either. The PCM's ability to adapt and adjust the fuel mixture based on oxygen left in the exhaust is the reason higher octane rated fuel yields better fuel economy.

MR.Z06 · Jun 11, 2016

RLJ10X said:
Locally, Marathon is th gas to beat as far as mpgs. There are several of my friends and I believe the local Sunoco distributorship waters down their gas. I've had good luck with BP, also.

When you say water down.
Do you mean dilute a 91 oct blend with 87 to increase profit?
Putting water in gas would ruin engines.

I'm not 100% convinced there's any difference in gasoline between summer and winter.

Not everywhere. I believe only 18 states?

GP4L · Jun 11, 2016

MANual_puller said:
I'm not 100% convinced there's any difference in gasoline between summer and winter. Warmer air, as indicated to the PCM via the IAT sensor, is less dense. The engine needs a constant A/F ratio so it will put less fuel into warmer air, thus helping fuel economy. Likewise that same warmer air that is less dense has less aerodynamic drag on the truck while driving, also helping fuel economy. I'm pretty certain this is why the same octane rating yields better fuel economy during the summer months.

Octane ratings are just that, energy/volume. The PCM will respond to fuel with lower octane in 2 ways, pulling timing initially as a response to detected knock to avoid detonation, and adding fuel as a response to oxygen levels in the exhaust as detected by the upstream O2 sensors. When you plug in a tuner and watch for knock retard you can monitor the quality of the fuel. If it's not retarding, it's likely not dumping extra fuel either. The PCM's ability to adapt and adjust the fuel mixture based on oxygen left in the exhaust is the reason higher octane rated fuel yields better fuel economy.

Generally, winter blend is made to evaporate at a lower temperature (for better combustion efficiency). It's easier for gas companies to make this fuel, which is why fuel prices are generally lower in the winter months. But it usually cant be used without drivability issues in warmer months. There's also an emissions reason for this too.

MANual_puller · Jun 11, 2016

GP4L said:
Generally, winter blend is made to evaporate at a lower temperature (for better combustion efficiency). It's easier for gas companies to make this fuel, which is why fuel prices are generally lower in the winter months. But it usually cant be used without drivability issues in warmer months. There's also an emissions reason for this too.

Octane ratings are still energy/volume. If your evap system is not holding pressure and letting the vapors out causing lower mileage that is no fault of the fuel. Gallons in are there unless they escape and with the same energy/volume of gasoline I'm concluding that the winter blend doesn't matter. That check engine light for the evap system makes a big difference.......there's a lot of vehicles running around with lax maintenance/bad gas caps.

MANual_puller · Jun 11, 2016

You've got to understand spring time here in Iowa to fully understand that winter blended fuel doesn't matter. First off, I've never experienced drivability issues with any vehicle. We'll have highs in the 20s and 2 days later highs in the 70s. I'm not filling my tank that often and I know the fillup stations are not switching their fuel that often either. We've had days in the 70s as late as Thanksgiving and have had frost as early as late August. It's all in your head. The fuel still as the same energy/volume.

GP4L · Jun 11, 2016

MANual_puller said:
Octane ratings are still energy/volume. If your evap system is not holding pressure and letting the vapors out causing lower mileage that is no fault of the fuel. Gallons in are there unless they escape and with the same energy/volume of gasoline I'm concluding that the winter blend doesn't matter. That check engine light for the evap system makes a big difference.......there's a lot of vehicles running around with lax maintenance/bad gas caps.

I think you missed something. And got righteous about something irrelevant to my last post.

Lowering/raising the evap point of the gas is for combustion efficiency. Fuel needs to vaporize during the process of combustion. Octane isn't the key point with that. Octane is a definition for how much pressure the vaporized fuel can sustain before spontaneously combustion.

Different fuel blends for summer and winter are for this reason:
When the air charge is cold (like in the winter months), the gas (regardless of octane) needs to have a lower evap point, so it can atomize, and then vaporize, yielding efficient combustion, otherwise engines would drivability problems like hard starting, lean mixtures, ect. When the air charge is hotter (summer) the evap point needs to be higher, so it doesn't cause the opposite drivability problems, like vapor lock, general rich conditions, poor emissions ect..

Gasoline volatility is regulated by the EPA, so you can read all about it on their website.

tjfdesmo · Jun 11, 2016

https://en.wikipedia.org/wiki/Reid_vapor_pressure

Using 89 octane for first time.

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