a couple months back i aquired my dads old 1990 toyota pickup. this thing had seen nearly 20 years of 87 octane. it started running rough in jan. of 09'...my dad parked it right then. it sat until i got it back in october. the whole time he owned that truck he never got better than 20 mpg..its a 4 speed (no overdrive)...after i got it i cleaned the carb and started it on a healthy diet of 93 octane. my last tank was 24mpg. the reason it was runing rough was from some trash in the carb. alli did was spray it out with carb cleaner so its not like its a fresh carb. 93 octane gave me 4 mpg over the 87 it has been running for nearly 20 years...i would say 93 is worth running. my stang gets nothing but 93 and all my hondas got 93 (they were turbo gsr's...3 of them)