Re: MPG info on 2000 Avalon


"Merritt Mullen" <mmullen8014@xxxxxxxxx> wrote in message
news:mmullen8014-C85F7B.22021530122005@xxxxxxxxxxxxxxxxxxxxxx
> In article <qgvbr1lfguidrv89gg68r3hb437iemibe9@xxxxxxx>,
> Gord Beaman <gord@xxxxxxxxxxxxxxxxx> wrote:
>
>> "sam" <noone@xxxxxxxxxxx> wrote:
>>
>> snip
>>
>> >> Sam...what does the owner's manual call for in fuel?...
>> >> --
>> >>
>> >> -Gord.
>>
>> >
>> >87 octane unleaded.
>> >
>>
>> Yes, OK...so Merritt is wasting money by using premium then...
>
> That is not exactly what the owner's manual says.
>
> What the owners manual actually says is to use 91 octane for best
> performance, but the minimum acceptable is 87 octane. If you use the 87
> octane (regular) the timing will be automatically retarded by the knock
> sensor (as necessary) to prevent detonation (pinging, knocking), and
> mileage will be slightly worse (less cylinder pressure, less efficiency).
> But that only comes into play when the engine is working hard, such as
> climbing a steep grade or under heavy acceleration. Since the price
> difference is less than 10% (20 cents) between premium and regular, I
> choose to use premium so it is there when I need it (when you are retired,
> money is no object--grin).
>
> I know about octane ratings and what they do as I am a retired Naval
> Aviator and I used to teach aircraft powerplants. Aircraft reciprocating
> engines are very sensitive to the proper octane fuel. AvGas comes in
> different colors so you know for sure what octane you are getting.
>
> Merritt

Your quote is not exact. On page 192 the manual says:
"Select Octane rating 87 or higher. For improved vehicle performance
the use of premium unleaded gasoline with octane rating of 91 or higher
is recommended."

The manual calls for 87. It says you can use higher. What car
is this not true for?

Than to paraphrase it says using less than 87 will cause knocking.
The manual does not say any of the other things that you mention.
The manual does not suggest what the improved performance
might be.

I interrupt the manual to say that 87 is fine. I have driven
the car 100,000 miles and have never felt a need for any
more performance. This has included to pretty tall and
steep mountains up to 14,000 feet. I consistently get
20 MPG city and 30 MPG highway. On one tank of
regular gas I actually got 40 MPG. The circumstance
for that was following my son who was driving an
overloaded UHaul truck.

Once I accidentally did fill with premium and noticed
no difference.

So I am open minded what performance improvement
can I expect to see? What sort of gas mileage can I
expect to see? I am a retired engineer for the past
13 years so the needless extra expense of $.20 per
gallon is a factor. The oil company profits are
high enough.

>From my engineering education I seem to remember
that higher octane gas contains fewer BTU per gallon
and unless the engine is designed to need the higher
octane the result will be poorer gas economy.


.

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