Question...
Why do people buy mid or premium gasoline, unless they have an auto with a high performance engine that doesn’t run well on regular?
I have a 2001 Impala LS (3800 V6) and the computer adjusts the combustion depending on the octane. I get full power using regular gasoline and don’t understand why people buy the more expensive octanes.
As you may know, gasoline formulation varies among states thanks to the Kafkaesque EPA.
In some states, the end product of refinement is not as, er, refined as other states. In fact, ‘reject’ gasoline is often moved into states with lower standards or less strict enforcement.
According to several mechanics of my acquaintance, one major difference between the grades is not octane - it’s water content. And there hasn’t been a gasoline engine yet that plays nice with H20. The deleterious effect is most pronounced in small gas engines e.g. lawnmowers but water is water.
Mid or high grade has less water if any at all and is a compelling choice in the states in question.
Because a lot of cars use premioum nowadays and using regular in them forces the computer to pull back the timing, therefore 'detuning' them.