Regular unleaded and premium unleaded fuel?

Question

With the rising fuel prices, I've seen a lot of questions asking if it's ok to put regular unleaded in a car that's designed to go with premium unleaded. I've heard from a mechanic that using premium unleaded in a standard everyday car designed for regular unleaded (eg a Corolla/Lancer) also increases its mileage, so in the long run it makes very little difference which type of fuel I use. Is he right?

Answer 1

I find that buying the regular unleaded and adding a fuel injection cleaner every so often to the full tank works just as well as premium and saves a bit of money over the long haul.

I think that which grade of fuel to use is up to the individual and what he or she feels is right for them to do.

Answer 2

if it says to put in premium, put premium in it or it could damage the engine

Answer 3

If you're car doesn't require premium octane, you're just burning up money by using it. You just won't make up for the extra cost at the at the pump. If you use 87 in a car that needs 91+ octane, you could damage your engine after time. You should only use what that car requires.

Answer 4

Cars that require a higher octane gas have engines that run with a greater compression than normal engines.  This compression would cause lower octane fuels to combust prematurely in the piston compression cycle and lead to damage to your cylinders.  You would know this is happening because it'd sound like a knocking engine.  The higher octane fuel would not benefit a normal (87 octane) engine and might even cause wasted fuel as it might not all ignite in the chamber.

So, use only the fuel that your manufacturer recommends for your engine.  It is nice to think that you'll get more speed or better fuel efficiency by using the "premium" fuels, or that you'll save money for using the "basic" fuel, but it simply isn't true.  The myth is too good to be true.