87 Octane Gas: Minimum vs. Recommended, & Benefits (if any) of Higher Octane Gas

https://www.tacomaworld.com/threads/regular-v-mid-grade-v-premium-experiment.374739/

I did a 3-year trial in my Taco running a year of each octane (87, 89, 91) using E10. Tried to keep the same station and same pump. After running 400+ gallons of each grade, I noticed very little difference in fuel economy. Someday I would like to hook my engine up a dyno with various fuel grades to confirm the hp/torque increase I felt.

Unfortunately, every discussion on TW concerning octane turns into a bunch of rhetoric and misinformation. You commonly hear poorly sourced information like higher octane contains more detergents (it doesn't) or engines run the same so long as the minimum octane is met (which was true prior to computers and VVT). TopTierGas is a marketing company.

 

We all know that 87 grade means 87% purity in gas and 13% impurity, and as for any higher grade. Lower grade gas causes slower spark, which results "ping" when go up hill since 87 lacks that many % of purity to give a necessary power to push the truck up hill in that variable time. That's the reason why they tell you to use higher grade octane. Impurities can't convert power, only gas can. So it will make your truck run smoother with higher grades, but not much better in mpg. If you take that to the law of thermodynamic. It says: mass in =mass out. In this case it is mas/volume converts into energy. I learned that in my sophomore year in chemical engineering. I always use 87, but I use 93 whenever I go to mountain or use it with additives to clean internal parts.

 

This/\
93 will help in mountains, less pining so truck will be able to stay on higher gear. Also on flat road you can let engine run low rpms on top gear. So lag the engine to get some crazy MPG.
In winter 87 because it vapors better so you lose less fuel on start ups (you know that gasoline smell in winter)

I think people should run what their conditions demand. Its very hard to say "one way or another"

 

Yeah, information and opinions on this are all over the place. I've tried all three grades for varying amounts of time when I first bought the truck, and there wasn't any major MPG differences. The 87 pinged or knocked at times, and the 93 didn't perform any better or different than the 89/91 middle range stuff dependent on where I was traveling. So, I just run 89 all the time every time, and 91 in places where that is the "middle button" at the pump. I don't care for loss of performance, no matter how minimal, and I especially don't care for engine ping/knock, so I run just high enough octane to avoid that.

 

I get 91 cause its ethanol free

 

Energy can neither be created nor destroyed; rather, it transforms from one form to another

 

Wish I could find Ethanol Free Fuel around here, I would probably have to travel a full tanks worth of gas to get to the closest station.

 

http://pure-gas.org/index.jsp?stateprov=SD

I think they also have a phone app.

 

Thanks I appreciate it, I have looked there before and the closest station was well over 100 miles away.

 

In this case, an enclosed engine, we create energy by burning fuel. We then destroy energy by making our Tacoma in motion, not all because it looses some through heat. You don't transform but you convert it. Remember we are talking about Physic here. So in theory, we can design any engine to have +95% efficiency, but practically it is almost(or not) impossible to do because we can not heat up and cool it down in an instant. Another word is that if you can create the most differential in temp in unenclosed system, you make the most efficiency machine. That is science and science doesn't lie. So higher grade only mean more purity and it will give you very little increase in energy=>power. But through heat lost it may not worth the cost of paying more for it to gain power/mpg. IT IS THIS MACHINE NOT CAPABLE OF OR DESIGN FOR!!!

 

Fuck thank you finally somebody understands.its as if you spoke word for word right from a text book. I remember all that from school. And you nailed it perfectly

 

I've given up on arguing the whole "higher octane better power/mpg" subject with people. But I strictly believe that it's a waste of money to put anything other than what's recommended by the manual into your tank, unless you have performance upgrades that necessitate it.

Best thing you can do for your truck if it requires 87 is to buy 87 at a top tier gasoline station. Buying 87 at Shell will be better for your engine than buying the cheapest 91 you can find at a discount station. Go ahead and buy the 91 at Shell if you want, but it's a waste of money, assuming you aren't super/turbocharged.

...I guess I haven't given up arguing it after all

 

I buy 91 cause its ethanol free , the Shell V Power 91 gets me my best mileage

 

Unless it's specified per the manufacturer I think it's purely a psychological effect putting anything over the rated octane into the tank. I believe 2nd gen manuals stated the engine (or more likely the ECM) was mapped for premium but was also capable of taking regular unleaded. As far as added detergents in premium, you're likely fooling yourself. Pretty much all gas is refined at a couple major refineries and distributed with different additives per whoever is selling it so you're getting the same add package regardless of octane. Whether ethanol skeeves you into premium is your own deal.
In my personal trials via the butt dyno I noticed a little more get up 'n' go and a TINY bit more mileage per gallon but not anything that would compensate for the increased cost. Law of dimishing gains etc. but it's your money so dump it where you see fit!

 

Never mind! I'm good! I don't need any!
Ummm, on second thought. Doesn't the ECM need more than one tank to make any adjustments for higher octane? Like using 93 to climb a mountain? Never mind.

There...
Fixed!

 

Uses knock control to determine timing advance, since it does not have an octane or ethanol sensor/analyzer. Within a specified minimum and maximum range.

Not all gas stations are equal. Not all climates, elevations, and density altitudes are equal.

 

Well I am now wondering if those damn race cars have ECU. If they do, I don't they we will win any race. No you do not need more than one tank because the computer is capable of detecting then make any adjustment, if the system work correctly. When you are at low speed and suddenly up hill, you can fool the ECU by pressing the gas pedal harder. The ECU thinks that you are at start up. It switch gear then no ping. Have you ever heard a single ping at start up? If you keep the same pressure on the pedal=> same gear and ping. This is where higher gas grades give you the benefit. So the question is how often you get that benefit

 

Yeah man, it 's a 20 years old book. It's my favorite one because it's a fundamental of all mechanical and chemical engineering. But I am in chemical.

 

THIS. It comes down to spark advance and knock sensors. Higher octane fuel IS capable of providing more power if your engine is designed to run with a higher compression ratio, because higher octane fuel can be compressed more than lower octane fuel before it ignites. If low octane fuel is being burned in the Tacoma's engine, it creates knocking, which is detected by knock sensors, causing the spark advance to be altered to create less compression. Less compression means reduced power. This is perfectly fine in most normal driving conditions but it's recommended that higher octane fuel is used for towing or in the mountains.

There is a limit though, depending on the optimal compression ratio the engine is designed to run at. Read your owners' manual to find what it is for your truck and decide according to your needs.

TLDR:
-Lower octane is fine for normal driving if there's no knocking. The engine will adjust.
-Higher octane is optimal for towing and/or mountain driving.

 

You will probably just get more ethanol around here if you run premium. They use ethanol as an octane booster. There is a station in east Texas that sells ethanol free in regular only. The reason they do this is premium has ethanol mixed on the truck. I run a high compression Mercury OB that requires 92 - 93 octane. Last tme I stopped at this station I had to buy octane boost to run the non-ethanol fuel.