i have always been using shell exclusively....i never had problem all the way to redline.Toad[^_^ wrote:]I've been running nothing but 93 octane Chevron with Techron since August (the life of my RB25DET) and I've had a problem around 5ooo rpm. Tonight my friend offered to pay me in gas for driving around all day and insisted that I stop at a Shell station nearby because my tank was almost empty. I put 3 dollars worth in and got back on the road. The results were instantaneous. The car once bucked and shuddered approaching anything slightly over 5000 rpm but now it begs for more throttle all the way till 7000. Has anyone else experimented with different gas stations? I hear that Quick Trip has decent fuel. I guess that the next step would be to try a bit of race fuel.