Gasoline

[25 IS V8]

I've driven the car like I stole it ... daily. I have never reset the Drive Computer. I use 91 octane from Circle K, mostly. 91 is the highest I have found around here. This is what the dash shows a few minutes ago. I drive 1 mile to the highway to work, 30 miles daily ... 28 on Hwy and rarely at speed limit.

First Run
Second run

And yes, it is still 96F at 10PM Local time ... desert SW

That is absolutely brutal weather! Where exactly DO you live? And in regards to Circle K 91 octane, I would verify where they get their gas. I try to only use Shell V Power or Chevron Techron in my IS. The additives in those brands really help, but of course they do cost more. To me, the cost savings is worth it to protect my engine.

I'm blessed to have an engine that has both port and direct injection so I don't have to worry about carbon buildup. The Z, being direct injection only, probably needs high-quality gasoline if you can find it.