Octane confusiuon...

So looking through my owners manual I was stumped by the Octane rating to use.
Is it 87 or is it 91?


After some research I found it's 87 in the US which uses the Minimum Octane Rating (MON) and 91 in countries that use the use the Research Octane Rating (RON).

This is much more helpful as I read it as, use 87, but then research how 91 works for you. LOL

 

Stock its 87 in the US

 

Yes, exactly, 87 is good, you can see how it performs with 91... LOL... I use to do it when base prices were equivalent to 87 price outside the base

 

I do 93 based on others research that the timing is retarded with 87 octane. It's in the DAP tuning thread

 

Before I installed my supercharger, there was a notable difference in drivability between running on 87 and running on 91. That being said, California gas is hot garbage, so your mileage may vary (literally) if you live in a state where your gas isn't terrible.

 

Would a stock tundra see notable mileage increase running higher octane?

 

I saw a 0.5 to 1 mpg increase, which isn't enough to warrant the additional cost. What did warrant the additional cost to me was the perceived "smoother" running of the engine, especially under kick down scenarios.

 

Pumps in North America show the Anti Knock Index (AKI), which is the average of the Motor Octane Number (MON) and the Research Octane Number (RON), which are just two different ways to measure the octane. I believe pumps in Europe show the RON.

 

Well if you figure 1 mpg would equal about 20 miles more a tank, plus the .20 cent premium each gallon would be about 4 bucks more per tank. 4 bucks is a gallon of gas here, looks like it would make sense under those conditions, plus you get healthier gas the whole time.

My 4.0 ranger used to run bad when I accidentally put 91 in it a couple times thinkin it was my Z. Maybe I'll try the 91 on the tundy for a tank.

 

In theory no. Octane ratine is not related to BTU content.

However, I would offer that those who are concerned enough about MPG to buy 93 Octane are likely altering their driving habits enough to see a slight increase in their MPG. I know most will say they drive exactly the same way, but my gut tells me otherwise.

As for prices, here in TX we have 87, 89 and 93 available at most stations. 89 will be about 0.30 more than 87, and 93 will be about 0.60 more per gallon than 93, so even IF 93 provides better mileage, it would have to be a huge increase of 20% or more to make it cost effective. That is not happening.

And for those of you who buy the mid grade, understand that your gas station just has two type of gas below ground, the 87 and 93 in our case. When we buy the 89, the pump pulls gas from each tank and blends is proportionally to achieve that 89 octane rating. Of course for us that would be 67% of the 87 and 33% of 93. However, our price for the 91 is consistent with a 50/50 blend. Hmmm.......

 

I noticed the same thing when I tested 91 in 2012 Tacoma 4.0. But like you said financially it wasn’t worth paying for the 91 octane.

Ethanol free gas...GAME CHANGER. Or at least it was with New York fuel.

 

To reiterate my original post, I saw 2 numbers 87 and 91. I discovered those numbers represent 2 different octane rating systems and figured I'd pass that information on.
Moral of the story, 87 octane is what it takes here in America.
As far as putting in a higher grade, it's not going to hurt, but it doesn't provide enough benifit to be worth the .60 a galllon increase in my opinion.
My favorite youtube mechanic is Scotty Kilmer and here's some videos of him speaking on the subject.
https://www.youtube.com/watch?v=pNGNoIiu-C8
https://www.youtube.com/watch?v=9zfE01wRcG0