87, 89, 91 ???

I get 20-21mpg hwy on 87 doing a roundtrip of 62miles per day. Got 18-19mpg on 90octane fuel(highest you can get here in AK). I've tested and confirm, if you drove as much as I do. You'll be figuring out all your MPG values. I drive 62miles a day for 5 days sometimes 6 days a week hwy going around 70mph.

With the higher octane I noticed the fuel doesn't burn as clean, this might have cause my drop in mpg. Everyones results will vary, different elevations and so on so fourth. So now I only use 87, saves me money and saves me fuel. Using 90 on my Lexus however nets me better mpg than using 87.

 

My subaru had the D4S with a turbo at high compression, required premium, but loved 94 with ethanol. I will be experimenting for sure. Usually I get more power out of the 94 blend, but less mileage.

I know a lot of 2nd gen owners who swear by 91 octane in canada. Especially where I am that has the higher elevation.

 

Exactly this, higher octane does not help unless your engine is designed for it. In extreme cases it can actually hinder performance. Most likely however you're not going to see much of a difference besides a lighter wallet. You can put 91 in a motor designed for 87 and get away with it but do not put 87 in a motor designed for 91. You'll destroy the engine.

 

The only one you got correct is 91.

 

I would rock a fat head of that avatar.

 

Pure ethanol has an octane equivalence of around 110, this allows for more aggressive timing and higher compression. The trade off is ethanol contains roughly 10% less energy per gallon resulting in lower mileage which is exactly what you saw.

 

If this engine contains a knock sensor, which I would imagine it does, it can adjust timing slightly if it detects pinging/detonation as a result of either lower than normal octane fuel and/or carbon build up which increases compression making the existing octane fuel not sufficient for normal operation/combustion. The result is it can retard the spark timing slightly to reduce or eliminate pinging/detonation to protect the engine from damage of compression ignition, and not spark ignition. igniting the mixture. By retarding the spark timing, you reduce performance and resulting fuel mileage slightly. So obviously, it can go "the other way" as well - it can advance spark timing slightly to a point to improve/get optimal/better peformance/mileage. Having an 11.8 to 1 compression ratio says to me that it CAN take advantage of higher octane fuel for a performance/mileage increase.

Today's engines are significantly more advanced as you all know. They have tighter tolerances, and extract more power from smaller displacements. They do this through various engine technologies combined with higher compression ratios, sometimes turbo or super chargers depending on the engine or manufacturer, etc. All in all they are demanding more from less. This saves weight with a smaller engine, saves fuel with less displacement, etc. And yet "y'all" (American lingo, sorry, I'm Canadian) expect 87 octane and good old conventional oil to stand up to the task of running the engine properly and protecting it properly because that's what you expect. Sure fuels have gotten better, oils have gotten better, but there is MUCH less room for error in these engines with all this crap in a smaller package.

 

I'm sorry your timing was impeccable.

I don't know if you noticed, but this entire thread (and forum) is dedicated towards people - mostly owners of a Toyota Tacoma - who overthink things which is why they are here (they value the driving experience and maintaining/upgrading their vehicle along with sharing information to help each other on various aspects). The people that don't overthink things do not participate or read vehicle based discussion forums, nor do they care to the level we do.

You could post the exact same thing in every thread and you would be right. Hell make it a sticky! We're all overthinking things! Woohoo

 

Christian, Clearly you've missed the point so, I've attempted to help you understand by inserting my interpretation (see quoted bold red text)...hope this helps.

 

The economy in the rockies is so terrible, people had to resort to using 85 octane. I personally just run diesel for the best MPG possible.

 

I use 91; no ethanol.

 

It already exists. Every car that is a "flex fuel" vehicle has one from the factory. They are also sold in the aftermarket for people with a programmable ecu that want to run E-85. It is needed if you have a partial tank of one fuel and then add some of the other. What is the ethanol content? It is measured in the fuel line going to the engine so the ecu can compensate.

 

I've used 87 exclusively for over 33 years, without regard to the manufactures recommendation, with no engine trouble.

 

Yeah, and all those people that swore off the "BIG 3" with multiple problems, issues, etc, and came to buy a more expensive Toyota because they are more reliable - they shouldn't get worked up either eh?

 

You're really being too nice with your interpretation.... lol!!!

 

The manual states 87, there's no evidence that it does advance timing or anything if you use a higher octane fuel. A knock sensor doesn't work backwards in that it just advances timing more and more if it never detects a knock. All it does is immediately cut timing to to help.

 

Most vehicles only need 87 and many modern engines in cars automatically compensate for drivers putting low octane in. Only vehicles that can't really compensate are motorcycles and older performance vehicles.

 

I heard that using below 91 octane in a 2016 Tacoma will void the warranty.

 

Only in Mexico and on Sundays.