Peter Jenkins wrote:
> I am taking delivery of a new Accord Euro ( in Australia ) on July 13. The
> brochures say Premium Unleaded ( PULP) fuel should be used. I cannot get a
> consistent answer from Honda dealers as to whether 95 or 98 octane PULP fuel
> should be used. My specific question is - have any tests been done to
> definitively establish whether 98 octane gives better performance and/or
> fuel economy than 95 octane. Does anyone have personal experience using the
> two fuels that they can share ?
>
> Thanks
>
>
honda's run on the cheap stuff unless you have one of the "r" spec vehicles.

regarding performance, if you check out oil company web sites and drill
down deep enough, you'll find that higher octanes do have a [slightly]
higher calorific value. this means that you should get [slightly]
better performance out of a higher octane gas. but the same web sites
[correctly] go to great length to emphasize that octane numbers are
about knock resistance, not performance, and will also say there is no
discernible difference.

my view is that it's only worth bothering with higher octane if your
engine has a knock sensor. if it does, the ecu can advance timing to
take advantage of the higher octane's burn characteristics. if it
doesn't have a knock sensor, stick to the octane it says in the owners
manual. and even then, examine the economics. even if the lower octane
does yield slightly less energy, i'll bet the percentage difference is
less than the cost differentail for the higher grade.

i'd also say that it depends on the car. hondas are very gas quality
agnostic. a french car i had in europe was /very/ gas sensitive.
ridiculously so in fact. again, this points to using the cheaper stuff
in the honda.