switching from premium to regular in 2006 GS300 V6

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.......

Reply to
kitzler
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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.

Reply to
dan

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.

Reply to
old man

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:)

Reply to
Me

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-

Reply to
Jay Somerset

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......

Reply to
kitzler

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.

Reply to
Elmo P. Shagnasty

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