In article <1119750302.303680.110150@g43g2000cwa.googlegroups .com>,
"SG" <Shur007@gmail.com> wrote:

> Hello!
>
> I recently bought a Honda Civic Hybrid 2005 and its User Manual says
> that "Gasoline Grade should be 86 or higher", which means any grade
> above 86 which could be "Regular 87", or "Mid-Grade 89" or even
> "Premium 93" can be used, as I understand. If I use "93 Grade
> Gasoline", will it do any harm to the engine? What are the pluses and
> minuses in using the "93 Grade"? What would you recommend and why?
>
> I thank you for your time and will appreciate your advise.
>
> Regards,
> SG

They'll all run the same so go for the lowest octane from a station that
sells fresh and clean gasoline.

Older cars are more sensitive to the octane rating. Their
air-fuel/emissions systems are operated by mechanical vacuum controlled
valves that are out of adjustment without sea-level air pressure behind
them. You had to reduce the octane at high altitudes to compensate for
the extra EGR and retarded ignition timing.

Newer cars use several feedback systems so that the engine runs at its
best under a wide range of conditions.