>I think that 89 is the way to go***as long as you do not get 'knock' during
>normal operation--not during hard accel, but during normal use if no or very
>small knock...will be fine.
The car should have a knock sensor that will take care of it (though
this necessarily compromises efficiency), but I can't agree that *any*
amount of knock is fine. What you are hearing is the result of a
shockwave being created in the combustion chamber.
Using a lower octane fuel than the engine is designed for can result
in it not buring progressively as it should, but instead it responds
to the pressure inside the combustion chamber by detonating with a
flame travelling at supersonic speed. This not only stresses the
engine components, but is inefficient. You may get away with it, but
it is not fine - it can be very destructive.
For best efficiency, use a fuel with the octane rating the engine was
designed for. If this is not available, use the next higher.

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Steve n Holly - 07 Sep 2004 17:29 GMT
The non turbo has a knock sensor?
> >I think that 89 is the way to go***as long as you do not get 'knock' during
> >normal operation--not during hard accel, but during normal use if no or very
[quoted text clipped - 14 lines]
> For best efficiency, use a fuel with the octane rating the engine was
> designed for. If this is not available, use the next higher.
AB - 08 Sep 2004 21:26 GMT
Virtually all modern electronic engine management units have knock sensors
these days...
It helps them to get optimum economy and performance from the engine.
> The non turbo has a knock sensor?
>
[quoted text clipped - 18 lines]
>> For best efficiency, use a fuel with the octane rating the engine was
>> designed for. If this is not available, use the next higher.
Steve n Holly - 09 Sep 2004 19:34 GMT
Please answer the question, a general statement is not an answer.
Does the non turbo 2.9 have a knock sensor?
> Virtually all modern electronic engine management units have knock sensors
> these days...
[quoted text clipped - 22 lines]
> >> For best efficiency, use a fuel with the octane rating the engine was
> >> designed for. If this is not available, use the next higher.
Bob Noble - 10 Sep 2004 22:02 GMT
Yes, the 2.9 non-turbo does have a knock sensor fitted - as does just
about any car that's fitted with an onboard computer. This allows the
advance curve to run at the optimum for power and economy.
bob noble
Reno, NV, USA