Gas prices are going down, but still expensive for premium gasoline. My car's manual says I should use high-octane (91-93) gasoline. I want the generic version. Can I do it?
Do you think the engineers are just playing a practical joke on you? If they say to use 91 or higher octane, then use it. If you have a high compression engine, using a lower octane causes detonation, what some call "spark knock." That is the sound of gasoline exploding before the spark plug lights it up. What this means is that the gasoline burns early, and a flame front travels down to meet the piston on its way up. You are actually hearing the result of that collision. It is like smacking the piston with a hammer.
This is nothing like the controlled burn that happens exactly when it is supposed to happen, when the spark plug lights off the mixture, pushing down on the piston at the correct time.
Anyway, detonation can break the piston and ring lands, but, more importantly, it will hammer out the rod bearings (top half) over time. I have personally witnessed this many times. You tear down the engine after it starts knocking, and the top half of the rod bearings has lost all of its coating.
Bad news.
For everybody else reading, your car probably does not require 91 or 93 octane. That is because YOUR car is designed to run on a lower octane rating.
For you, Bluehouse, your car needs it. They designed it expecting high octane to be used. Lower octane will pre ignite. It can survive this for a while, especially if you drive very easy with no hard acceleration, but over time you are hammering those rod bearings out.
If you do not like buying high octane gasoline, then just buy a car designed to run on regular gas. Most of them are, so it will be an easy switch.