Does 87 octane vs 89 octane really make a difference?

[seabrook]

They might all burn down to a "silence" as you call it,but they also don't create the same btu's as gas.And I would have to disagree with you on how clean they burn,when I mix 5 gallons of 114 race fuel in with 10 gallons of 94,my plugs are coated in white flaky crap,that carries right out to my tail pipe tips,and you're telling me the chemicals added to slow the flame front down,but leave a white flaky residue all the way out to my tips,is a clean burn,yea don't think so bud.I lean towards trusting what my uncle said about high octane fuel being a dirty fuel,he was a chemist for to many years not to know what he was talking about,lol.BTW what is your position in the refinery?

The white flaky stuff is additives. I am a sr process control specialist / sr SIS specialist

 

[Average_gatsby45]

i know in all my 4 cyl trucks, that lil extra oomph really made a difference in performance

 

[tom martley]

I have a 2019 Ram Limited 5.7 1500 with 3.92 dif. My book says 87 octane is ok but best performance achieved with 89. I was using 87 so switched to 89, and it roughly increased mileage about 2 mpg. Cost for 89 octane over 87 is about $.20 gallon more. 87 octane gets me about 15 mpg in town, 89 about 17 mpg in town. So, do your math, mpg using 89 is better and you can save a small amount of $. Much more then $.20 is either break even or a loss.

Highway mileage is about 18.5 to 19 mpg on 89 octane. Truck has never seen anything near 21 mpg. Running A/C costs me about 1 mpg

 

[Lucy Girl]

I've been running the recommended 89 octane, but I was curious on whether or not I'm spending the $8~ on nothing. I am currently getting roughly 15 - 16 mpg city driving.

AGAIN. PLEASE STOP WITH OCTANE QUESTIONS. THANKS

 

[stevehhll]

My old commute used to include a long hill that my manual xmission DD would sometimes not make without disconnecting the CC due to speed decline. I checked it literally hundreds of times with different octane fuels. With premium it would not make it as far up the hill without kicking out the cruise control, so I know for a fact the premium fuel hurt my performance (aka mpg). However, with today's computer control systems, if the book say use 89 octane I'd use 89 octane. Using lower octane might make it knock a little before the control system adjusts and bust a weak link somewhere.

 

[RASelkirk]

I did a hand calculated milage analysis for 87 for 2 weeks then 89. Posted it somewhere in here on someone elses thread. I got about 2mpg less on 87, and like he just said... didnt run as smooth. That being said Im running a 93 tune now and will probably never go back. Its about 4dollars more every time I fill up.. which is less than a good coffee.

Sent from my SM-G960U using Tapatalk

I've always used 91 (I don't drive much so cost is not a factor). I tried about 3/4 of a tank of 89 last fill up and my overall mileage gauge dropped from 13.8 to 13.3 in two days...

Russ

 

[Mfg521]

It really depends on where you live as well if you live at higher altitudes you need less octane I live just over sea level and I have bin running 93 because I get a better performance and more gas mileage and can get it for around $3.10

 

[Lyle Longboat]

Speaking of gasoline numbers, does anyone ever use additives such as Lucus or any other brand? If you do, do you see any difference in numbers with or without?

 

[boblonben]

I'd hazard a guess the majority of trucks are filled up with 87,lol. I run 87 in my wifes 2016 5.7 Challenger which is the same as the trucks,89 reconmemded but 87 acceptable.Car runs the exact same numbers at the track on 87 as it does on 89,and actually slows down if I fill it up with 94.It also gets better milege on 87,as 87 is cleaner fuel.The additives added to increase octane numbers,don't burn worth ****,and will slow the combustion chamber burn down.I had an uncle who was a chemist with Mohawk for years,and he used to describe high octane fuel as "dirty" fuel because the additives don't burn all that great compared to gasoline

nice to read from someone who actually knows the difference!!!!!

 

[Casper]

I run both octanes and can’t really tell much difference. Haven’t noticed any knocking with 87. I usually run 2 tanks of 89 to one tank of 87. If I’m filling up at Sams it’s 93 or 87. Use both here as well.

***
Before I installed a catch-can I would sometimes get pre-detonation with 87, and feel the PCM pulling timing.
Now that all that blow-by isn't entering my intake, I run 87 all the time. 89 gives me no better mileage or power.

 

[scott lass 18]

I've been running the recommended 89 octane, but I was curious on whether or not I'm spending the $8~ on nothing. I am currently getting roughly 15 - 16 mpg city driving.

 

[Casper]

Speaking of gasoline numbers, does anyone ever use additives such as Lucus or any other brand? If you do, do you see any difference in numbers with or without?

***
I use Techron every oil change and Seafoam into the throttle body Spring and Fall.
Yes, I do notice a difference after Seafoam. Techron, not so much. But that's prophylactic, to cut deposits, keep injectors clean and take up water (condensation) in the fuel tank.

 

[scott lass 18]

i started 89 oct cus the truck just ram sooo much better when new no shaking and would pick up faster i feel ! i then went to 91 and a programmer for years now runs so great and did mod s on it so faster and great power now ! wish they had 93 in californa i d do even better i feel hemi has two spark plugs burns it all my smog test cam out better then new too !

 

[Retiring Don]

'19 Ram with 3.92 gears and 12K+ miles. I've done the mileage test with 87 and 89 octane and didn't find any difference in city or hiway mileage or performance. I get 14 to 16 mpg around town and 18-20 mpg on the hiway without a tow, depending on how fast I drive. So what I do is run 87 when driving around town or hiway without a tow. Then when I pull my travel trailer on a trip I use the 89 due to the added strain. Seems to work for me.

 

[Retiring Don]

'19 Ram with 3.92 gears and 12K+ miles. I've done the mileage test with 87 and 89 octane and didn't find any difference in city or hiway mileage or performance. I get 14 to 16 mpg around town and 18-20 mpg on the hiway without a tow, depending on how fast I drive. So what I do is run 87 when driving around town or hiway without a tow. Then when I pull my travel trailer on a trip I use the 89 due to the added strain. Seems to work for me.

 

[Bbtl10825]

Over the life of my truck..2018 Hydro Sport...I'm getting around 18.5 mpg.. most of my travel has been highway.. however I do like to play as well.. I use the E88 blend. No knocks not running rough either.. but I only have about 18k on the truck with the high gear rear end 3.21 I think.

 

[marks146]

Octane isn't mileage. It's anti-knock. think "smooth explosion vs. two firecrackers tied together. I get clattering (two firecrackers) on some 87 octane pumps, depending on the blend they happen to get delivered. With 89, I don't. YMMV

I agree with Ghost. And when I tow which is the main purpose of owning this truck it makes a difference in reducing knock. I've run 87 for 6 months when I first took ownership of the truck and as stated above it made the clattering noise when under power such as pulling out from a stop or towing. I also try to fill up at stations that dispense TOP TIER GASOLINE which guarantees detergent blends.

 

[moulin6801]

My 2014 Hemi has 140,000 miles
Drive like new, pull very strong!
For the first 1000 miles I was noticing the engine pin noise with 87oc, so I changed start using Shell 93 oct. and never looked back!! I think the gas mileage may be 1 mpg better, but I don’t even care about that! I love to whenever I feel like, just flooring it and not worry about the poor engine pinning! Besides, it have been a good investment, since I have never spend 1 dine on mechanic, just oil changes & tires.
I have a crew cab Laramie.
PS, once I used Wal-Mart 93oct and start to Pin again... so, screw the cheap gas! Not worth it.

 

[Lucy Girl]

Speaking of gasoline numbers, does anyone ever use additives such as Lucus or any other brand? If you do, do you see any difference in numbers with or without?

Lucas every time, without fail. Don’t do the numbers thing anymore.

 

[JimE]

I've been running the recommended 89 octane, but I was curious on whether or not I'm spending the $8~ on nothing. I am currently getting roughly 15 - 16 mpg city driving.

The computer in your truck will adjust timing (retard) when necessary to eliminate knocking. That adjustment may result a minor loss in mpg. I never buy anything other than 87 Octane.