I have a 91 5.0 vert. Car is great, runs great. I have run 87 octane in it, which is what the gas cap calls for. COULD I run a higher octane without hurting the car? Or even occassionally run a higher octane, like for a long trip?

 

Higher octane when not required will only hurt your wallet. There is no point in running higher octane in an engine that requires 87.

 

that is unless the car is showing signs of knocking. a lot of times the compression will change as miles are put on a car, which may lead to knocking when using 87 octane gas.

 

yeah, just stick to 87