Does the octane rating of gasoline affect the internal engine temperature? I was stress testing my A/C last week (100+ for the afternoon commutes) and I had to get some gas on Wednesday. I had been running 93 octane, but I put some 87 in because I am poor. Well, it seemed like the A/C worked MUCH better on Wed, Thurs and Fri than it did on Mon and Tue. The only thing that changed was the gas. The temperature and humidity were approximatley the same all week. Is it possible that the octane rating had anything to do with this, or was the heat finally getting to me?