What gas grade do you use!?

Thank you for reminding me how higher octane ensures pre-ignition does not occur in high compression engines. I will use a lower octane to for a few months and see if there is any noticeable gain or loss in fuel mileage.

 

I did a little research and found this information regarding octane to compression ratio. Other research may provide slightly different numbers.

87 Octane - engines with 7:1 t0 9:1
90 Octane - engines with 9:1 to 10:1
92 Octane - engines with 10:1 to 11:1

I could not find a specific listing for 89 Octane, but based on the numbers above I would estimate:
89 Octane - engines with 8.1 to 10.1

The 5th gen 4R V6 has a compression ratio of 10.4:1
Based on these numbers then the best two octane options would be 89 or 91 or even 92. As the gasolines with those two octane ratings would potentially provide the most fuel efficiency.

That having been said, the Toyota Manual says 87 Octane will work fine.

Since my habit has always been to use 91 octane, due to my previous vehicles having a need for it, I am going to switch to 89 octane for a few months and record my mileage to see how it compares. I suspect I will get the same efficiency with 89 octane. I don't know if my previous habits will allow me to go down to 87 octane. However, if the mileage results are the same at 89 as 91, I may give it a try. I always try to set my biases aside and see what the math tells me. If the mileage is the same, then the fuel of a lower octane is providing the same level of energy output. This test of lower octane fuels to determine mpg numbers does not necessarily indicate if the higher octane fuel is providing more hp in the form of torque. But I would surmise that for my driving style there would be no noticeable difference.

 

85...I try to fill up at Costco as much as I can.

 

Word is that guerrilla fighters and terrorists the world over love this engine cause it will run on anything, even the blood of infidels. Alas, none of my local service stations sell Blood Of Infidels. Just Regular, Plus and Premium. So guess I'm gonna stick with the old 87.

 

My salesman told me the off road premium needs premium gas.

 

Wonder if your salesman has pissed in a cup recently?

 

Is Kroger considered top tier? If not, then what about Shell because I get $$ off at both locations for shopping at Kroger. I just got my SR5 Premium a couple days ago & haven’t filled it yet. But I don’t wanna go to someplace that’s not top tier.

 

Shell is top-tier and is excellent fuel.

 

This may help you.

 

One would have to know the details of the software in the ECU to know if a 4-Runner even might benefit from higher octane. It's an older, proven engine with a relatively low compression ratio by modern standards and I doubt that it advances timing until it detects knock...more likely as someone stated the calibration has conservative spark timing that assumes 87 octane and uses a knock sensor only to retard spark in very rare extreme use situations (if ever). I had an air cooled Ducati and the dealer recommended that I use 87 because it burns faster than 93 so in that bike (with no knock sensor) it might make a tad more horsepower. I'm a former powertrain engineer and run 87 in my 4-Runner. My vehicle rarely sees wide open throttle.

 

Very useful information for a novice like me. Thank you!

 

Cheap stuff- 87. Though once I did get ethanol free gas just cuz.