switching from premium to regular in 2006 GS300 V6

[kitzler]

Not that an extra couple of bucks per tankful will break me, but I just
read an article by M. Niedermayer in "Truth about cars" stating among
other things, that using regular gas instead of premium in a high
compression (11 to 1) engine would not affect performance or mileage by
more than a percent or two. He went on about not changing your oil,
but perhaps only once a year, as today's oils and today's engine are
tuned to avoid sludge formation and crankcase contamination, but that
is another story. I just would like to send out a feeler to see if any
of you folks have had good or bad experiences with using regular versus
premium gas in your Lexus'... I just hate enriching gas purveyors
unnecessarily.......

[d***@nospam.com]

Post by kitzler
Not that an extra couple of bucks per tankful will break me, but I just
read an article by M. Niedermayer in "Truth about cars" stating among
other things, that using regular gas instead of premium in a high
compression (11 to 1) engine would not affect performance or mileage by
more than a percent or two. He went on about not changing your oil,
but perhaps only once a year, as today's oils and today's engine are
tuned to avoid sludge formation and crankcase contamination, but that
is another story. I just would like to send out a feeler to see if any
of you folks have had good or bad experiences with using regular versus
premium gas in your Lexus'... I just hate enriching gas purveyors
unnecessarily.......

Modern engines will adjust ignition etc for lower octane fuel, but the
engine will not make as much power and mpg may be significantly
impacted. Try it out.

[old man]

Toyota/Lexus optimise their engines for the region it is sold in, and a
specific rating
On this side of the pond LPG is sold and cars not origonally sold to use it
can be adapted. We are told there is no detrimental effect.
However when I spoke to Toyota HO Tech I was advised that their tests had
shown it caused damage to the engine.
Not what you asked but you may be interested.

Post by kitzler
Not that an extra couple of bucks per tankful will break me, but I just
read an article by M. Niedermayer in "Truth about cars" stating among
other things, that using regular gas instead of premium in a high
compression (11 to 1) engine would not affect performance or mileage by
more than a percent or two. He went on about not changing your oil,
but perhaps only once a year, as today's oils and today's engine are
tuned to avoid sludge formation and crankcase contamination, but that
is another story. I just would like to send out a feeler to see if any
of you folks have had good or bad experiences with using regular versus
premium gas in your Lexus'... I just hate enriching gas purveyors
unnecessarily.......

[Me]

I was using 87 octane in my 2000 ES300 and the car ran fine. I tried
premium, and the car's gas mileage went up, more than compensating for the
increased price. Your mileage may vary:)

Post by kitzler
Not that an extra couple of bucks per tankful will break me, but I just
read an article by M. Niedermayer in "Truth about cars" stating among
other things, that using regular gas instead of premium in a high
compression (11 to 1) engine would not affect performance or mileage by
more than a percent or two. He went on about not changing your oil,
but perhaps only once a year, as today's oils and today's engine are
tuned to avoid sludge formation and crankcase contamination, but that
is another story. I just would like to send out a feeler to see if any
of you folks have had good or bad experiences with using regular versus
premium gas in your Lexus'... I just hate enriching gas purveyors
unnecessarily.......

[Jay Somerset >]

Post by kitzler
Not that an extra couple of bucks per tankful will break me, but I just
read an article by M. Niedermayer in "Truth about cars" stating among
other things, that using regular gas instead of premium in a high
compression (11 to 1) engine would not affect performance or mileage by
more than a percent or two. He went on about not changing your oil,
but perhaps only once a year, as today's oils and today's engine are
tuned to avoid sludge formation and crankcase contamination, but that
is another story. I just would like to send out a feeler to see if any
of you folks have had good or bad experiences with using regular versus
premium gas in your Lexus'... I just hate enriching gas purveyors
unnecessarily.......

My experience with my 2006 GS300 is that going from 87 to 89 octane
increases mileage a bit more than the cost differential, and going up to 91
or 93 increases mileage further, but not necessarily by as much as the cost
rises. It is much easier to measure this for highway driving than chugging
around in the city, as mileage in the city is much more traffic dependent.

I observed the same behavior with a 1997 Toyota Avalon, and a 1998 Audit
A6Quattro. For all of these cars, 89-91 octane was the "sweet spot" in
terms of cost per mile.
-Jay-

[kitzler]

Post by Jay Somerset >
My experience with my 2006 GS300 is that going from 87 to 89 octane
increases mileage a bit more than the cost differential, and going up to 91
or 93 increases mileage further, but not necessarily by as much as the cost
rises. It is much easier to measure this for highway driving than chugging
around in the city, as mileage in the city is much more traffic dependent.
I observed the same behavior with a 1997 Toyota Avalon, and a 1998 Audit
A6Quattro. For all of these cars, 89-91 octane was the "sweet spot" in
terms of cost per mile.
-Jay-

Thanks Jay, most of my travel is at relatively high speed, 50-70, and I
shall use your observations... it actually makes sense, by increasing
the octane you allow the engine timing to be advanced and doing so
increases power without damaging the engine valves.. I also worry about
Toyota's fling of using i, meaning they use fuzzy logic to do certain
things, in the case of the engine it is ECT-i which stands for
electronic controlled Timing with intelligence.. so monkeying around
with this logic may prove to be dangerous.. by the way, I disabled the
intelligence vector in my automatic transmission by switching to
driving in the S-mode, where Lexus allows the driver to limit the speed
range (downshift only sad to say) of the transmission, that way I avoid
having excessive engine braking when I take my foot off the gas......

[Elmo P. Shagnasty]

Post by kitzler
Not that an extra couple of bucks per tankful will break me, but I just
read an article by M. Niedermayer in "Truth about cars" stating among
other things, that using regular gas instead of premium in a high
compression (11 to 1) engine would not affect performance or mileage by
more than a percent or two. He went on about not changing your oil,
but perhaps only once a year, as today's oils and today's engine are
tuned to avoid sludge formation and crankcase contamination, but that
is another story. I just would like to send out a feeler to see if any
of you folks have had good or bad experiences with using regular versus
premium gas in your Lexus'... I just hate enriching gas purveyors
unnecessarily.......

The ONLY way to determine what fuel you should use:

1) read the owner's manual carefully. Does it REQUIRE 91 or 93 octane
gas, or does it merely RECOMMEND such gas?

2) run a few tankfuls of each type of gas, and calculate not only the
miles per gallon but also the cents per mile it cost you, in gas, to
drive the car with that gas. You may very well find that the lower
cents per mile fuel is the more expensive fuel to buy up front.

3) check your seat of the pants. Are you unhappy with the general
driveability of the car with one fuel over another? If so, how unhappy?
See #2 above.

If the manual does not REQUIRE a higher octane, or if the manual says
you can certainly run a lower octane without damage, then do the test in
#2. Do it over several tanks of each type of gas from a brand you
typically buy. (Hint: buy Shell gas. Trust me.)


As for oil changes....what is absolutely the cheapest form of insurance
you can buy for your engine? That's right, an oil change. Once/year?
That may be sufficient--but it may not be for YOU. Consider changing
that to merely twice/year. An extra $40/year is very, very cheap
insurance. Shoot, do it 4 times/year--the extra $120/year insurance is
very, very cheap.