[Ken99287]

just use 87, the high octane stuff is for cars with knock sensors and forced induction applications. example - using 87 in my saab only produced 18psi boost, but high grade produces 25(knock sensor lowers boost levels), that is because higher octane makes the fuel mix harder to preignite(ignite from being pressurized), ensuring that the mix only burns when the spark plug sparks. pre-ignition/detonation is bad because it's igniting during the compression stroke-very hard on engine parts. but regular cars only need the lowest grade needed to prevent detonation. the "Porshe" badge doesn't mean it's not still just a regular ol' combustion engine. just cuz it's a porsche don't mean high grade will do miracles. now if you had a 951...