Premium gas or regular?

WABBMW wrote: I agree that the ethanol is of no performance value, nor mileage value. I undrstand that it only has about 2/3 the power output of petroleum fuel. So if there is 10% ethanol in your fuel, and that 10 % is only 2/3 as powerful, then the ethanol will deliver about 96.7% of the power that full petroleum based fuel will do. Also, in humid weather, an open pan of the stuff will become cloudy within minutes, indicating that it soaks up water like a sponge (like somebody said).

But how can you fine any NON-ETHANOL fuel any more?

My '82 KZ650 runs the same regardless of the octane rating. I think that regular grade ignites a little faster that premium, similar to advancing your timing. So that helps, provided your compression ratio and timing are not too high or advanced. The debate goes on.......

LarryC wrote: Consider the situation where the high test gas you get out of the pump might not be very fresh. Many people don't buy it for their cars.....it sits in the ground tank. It's most likely ethanol blend.....moisture problem..

Motor Head wrote: Here is a read that some of you might enjoy on Octane and fuel. Get a cup of coffee and have a look.
www.faqs.org/faqs/autos/gasoline-faq/part3/preamble.html

6.13 Can higher octane fuels give me more power?

On modern engines with sophisticated engine management systems, the engine
can operate efficiently on fuels of a wider range of octane rating, but there
remains an optimum octane for the engine under specific driving conditions.
Older cars without such systems are more restricted in their choice of fuel,
as the engine can not automatically adjust to accommodate lower octane fuel.
Because knock is so destructive, owners of older cars must use fuel that will
not knock under the most demanding conditions they encounter, and must
continue to use that fuel, even if they only occasionally require the octane.

If you are already using the proper octane fuel, you will not obtain more
power from higher octane fuels. The engine will be already operating at
optimum settings, and a higher octane should have no effect on the management
system. Your driveability and fuel economy will remain the same. The higher
octane fuel costs more, so you are just throwing money away. If you are
already using a fuel with an octane rating slightly below the optimum, then
using a higher octane fuel will cause the engine management system to move to
the optimum settings, possibly resulting in both increased power and improved
fuel economy. You may be able to change octanes between seasons ( reduce
octane in winter ) to obtain the most cost-effective fuel without loss of
driveability.

Once you have identified the fuel that keeps the engine at optimum settings,
there is no advantage in moving to an even higher octane fuel. The
manufacturer's recommendation is conservative, so you may be able to
carefully reduce the fuel octane. The penalty for getting it badly wrong,
and not realising that you have, could be expensive engine damage.