gas questions for LS430

My recollection is the higher octane fuel provides an incrementally longer burn. If true it would seem logical that you could expect a very slight improvement in mpg from using the higher octane blend.

It's also harder to burn--which is the nature of its anti-knock properties.

Which leads to lower mileage in cars that are not designed SPECIFICALLY to use that octane level of fuel.

It goes to show what you really know versus what you assume is correct. There is a regulation on horsepower ratings. It must be tested with the fuel that is recommended by the manufacturer. This is even witnessed by a third party to ensure no bias. So Lexus would have to test the ES with premium fuel while the Camry would have to be tested with regular fuel.

I will answer your question. Toyota engineers the vehicle with the higher octane they have in Japan. That is why their engines are high compression engines. All one has to do is merely compare it to its competitors engines. Don't take my word for it, do your own research. To ensure that in can run at lower octane, they installed knock sensors to retard timing. This is to the detriment of power. Since the engine has to work harder, the effects would be more apparent in the long term.

These are facts and not opinions for those that truly know the automotive industry.

Answer this: You exclaim that Lexus markets a "lifestyle experience." Where is it that premium fuel is part of that? What proof do you have?

Ummmmm......OK......so?

And that has what to do with what the engine's management system was designed for?

So what you're saying is that the Camry and the ES, which use the same engine, are both designed for higher octane fuel.

But Toyota recommends regular in the Camry, while they recommend higher octane fuel in the ES. Does that make sense?

OK, so then you go on to say:

Which makes no sense whatsoever with respect to documenting lower octane fuel in the Camry and higher octane fuel in the ES.

Which leads me back to my original proposition: different fuel recommendations for the same engine is a marketing move, pure and simple.

"Premium" cars would NEVER be marketed to use something so mundane as a "non-premium" fuel. It all has to do with tying in to the fuel marketing crap of higher octane somehow being a "premium" fuel.

The engine management system has a lot to do with fuel quality and octane. Some of the variables controlled by the electronic control unit (ECU) include base ignition timing, spark advance, and spark retard in the event knock is detected, injector timing, and injector duration.

Even when the same engine designation is used, Toyota/Lexus does have variations among applications. For example, the 3.5 liter engine has direct injection in the IS and conventional in the Avalon.

The ECU controls base ignition timing. In an engine designed to use higher octane fuel, base ignition timing will be more advanced to take advantage of the higher octane while one designed for lower octane fuel will have less advanced base ignition timing and so it would not take advantage of premium fuel.

In the case of the 3.3 liter engines used in the Camry and ES, that statement would be true if both cars used the same part number for ECU's and long blocks.

In the case of the OP's question about the 4.3 liter engine used in the LS, there is no application in Toyotas sold in the U.S. so there is no direct comparison.

Since I have to spell things out for you: Lexus has more power because it has to use premium fuel as recommended.

See the response above.

They are not the same engine. They are nearly the same but not exactly the same. For example, Lexus tunes their engines more for 91 octane as their primary use. Both engines will have more power with higher octane.

Yes it makes sense. Toyota knows that Camry buyers have a tighter budget so they tuned the engine to use 87 octane primarily but engineered it to take advantage of premium fuel. Lexus engineers know the fuel costs isn't as big a factor to their clients.

See the responses above.

Toyota does not benefit from oil company profits. They could care less. They care about their cars and their needs.

Still no proof...just more biased conjecture.

Take this for example, Toyota runs a Celebrity race in California annually. They don't modify the internals of the engines. To give them more power, they use 108 octane fuel on the Celica's the used to use. This is the exact same engine that they use to sell at the dealers. Since you need it spelled out, the engines are built to take advantage of higher octane fuel right from the showroom floor.

Let's go back to what you read of your owner's manual: Lexus says use

87 octane fuel. For "more performance" (a vague statement with no details to back up what that means) use 91 octane.

What fuel do you call "premium"? You're putting 93 octane in your tank--even though Lexus doesn't say to under ANY conditions, even their vague "better performance" condition.

So you're one of those who think that "premium fuel equals more power".

It doesn't. But the fuel companies are happy to have you think that.

You also claimed engine damage when using the lower octane fuel, yet your owner's manual doesn't go anywhere near that.

Face it--you don't know what your doing or why. You just want to believe that higher octane equals more power (it doesn't), and you like the idea of spending more money for the sake of spending more money. It makes you feel rich.

Actually it is probably more like telling people NOT to put aluminum foil in the Microwave because it is easier to just say (don't) do it, rather than try to explain under what conditions it is okay ... than to expect them to understand/think. ... it is all part of catering to the lowest common denominator.

On Wed, 24 May 2006 06:07:52 -0400, "Elmo P. Shagnasty" graced this newsgroup with:

to add fuel to the fire (pun intended), here's a pretty good article on what octane level does to an engine and it's performance.

basically, yes.higher octane *will* increase horsepower, but only at the maximum output. In normal driving conditions, the difference between lower and high octane is minimal. Additionally, putting a higher octane rating than the maximum recommended by the manufacturer has little or no effect.

It actually has the effect of damaging the engine.

And where, pray tell, is your evidence for this somewhat unqualified opinion?

You could hear a pin drop when the almighty Jay Somerset addressed his adoring fans with these immortal words:

I can't speak for Elmo but I've read that putting high octane fuel in an engine that doesn't require high octane will cause excessive carbon buildup which, over time, will build up enough carbon on the piston heads to eventually *require* higher octane fuel.

Carbon buildup is caused by incomplete burns. This may be caused by a poor spark or a mixture that's too rich. The higher octane doesn't cause carbon buildup. That's probably a myth when someone thinks that the premium fuel has more "gasoline" mixture than standard unleaded.

You still offer no proof. You're one of those that merely speculates. You have no expertise on the subject. Even other responders have explained this to you yet to resist. You're beset with your own ignorance. Just don't pass it along perniciously to others like a virus..

The owner's manual, which you quoted, is clear that the requirement is

87 octane. Your stand, which you've made clear, is that you prefer to put higher octane fuel--that is, more expensive fuel--in your tank.

The math is easy.

And you have yet to back up or document what Toyota's vague "better performance" statement actually means.

Hmmmm....why would the gas not burn completely...??? What might cause that tendency?

The higher octane fuel is...let's see....think now....more difficult to ignite. That's what octane rating is.

Hmmmm.......

You know, you really, really want to believe that spending more money makes you better, happier, wealthy. So you do so, unnecessarily.

You could hear a pin drop when the almighty "Elmo P. Shagnasty" addressed his adoring fans with these immortal words:

One way to determine once and for all if these engines require higher octane is merely to find out what the compression ratio is. If the engines are, like most modern engines, low compression, high octane fuel has no effect except in the wallet and wasted fuel for inefficient combustion.

I did indicate the cause of this. Why did you leave it out? It would seem you need assistance in your reading comprehension.

People that know about chemistry would think that you're retarted. The higher octane simply means that it has less tendency to pre-ignite (or ping in layman's terms). That doesn't necessarily mean more difficult to ignite.

Wrong again. Would you like to go for double jeopardy where the points can really double?

Now who's avoiding answering the question? What proof do you have that Toyota is doing this more marketing reasons? Answer that.