why does the 2004 Totota Avalon use high test gas

You are out of your mind if you think I can't detect a difference in the idle between regular and premium. I've already said that the idle would be one area that I would not expect to notice a difference when switching grades of gas.

I agree, it's a tad peculiar, being as the engine is not under load. But there IS a difference in the idle when switching between regular and premium. Whether you think I'm crazy does not matter to me. I don't care. I know my car, and I can tell a difference. I'm not going to argue about this, as I'll never be able to convince anyone that can't be here to see and hear it for themselves.

WAAA, MATH IS HARD! Octane number is bigger, therefore must be better, therefore I declare it so. I put head in sand now.

Whatever.. What does the price have to do with anything? I'm not arguing which grade might give the most bang for the buck. I've never tested that, and don't really care too much as the difference in bang for buck would be quite small.

Who cares? I'm not interested in which gives the most miles per gallon. This has nothing to do with my claims of the engine running slightly smoother on premium, which you people seem to think is impossible. Go hump someones else's leg over this crap. I don't really care, being as I'm not claiming any particular grade gives the most mpg which seems to be what you are worried about.

no, he's not.

Your car does not "feel smoother" with "the good gas". It's not "good gas".

And higher octane does not cause valve timing to change.

I will be happy to conduct a blind experiment with you. I will take your car and put in the brand of gas that you specify but an octane rating that I specify. We will do this cycle for 10 tanks, using the same brand but mixing up the octane levels. You will record your "feelings" and what gas you THINK is in the car for any given tank.

What do you think will happen? I *know* what will happen.

You have already convinced yourself that "higher octane" means "good gas," and your mind is responding to that.

What are you babbling about now? Math is not hard. But I've never claimed any particular grade gave more bang for a buck than another. I DON'T CARE about that aspect. It's NOT what I'm talking about. I'm talking purely about the way the engine runs. So go hump someone else's leg. I'm not some dumbass that just fell off a turnip truck.

I'm done with this crap.. You obviously have your head stuck up so your ass it's blocked the flow of oxygen.

You are mistaken.

If there is a difference at idle between premium and regular, or mid-grade and regular, then the knock sensors are doing it. Knock is not detected with the higher grades so the timing advances. Knock, if there is any, is cured by retarding the ignition timing. I would not expect knock at idle, but there's no reason there could not be, so the knock sensors would detect it instantly and retard the timing.

I'll accept the premise that you can tell the difference at idle, but the valve timing is not why. It's ignition timing. Ignition timing changes with the fuel, valve timing does not.

But, the point here is that higher grades of gasoline can improve performance enough that the cost per mile to drive the car is actually lower with higher octane gas, UNLESS the car only calls for regular (87 octane) in the first place.

If your car calls for premium (93 or 91) or mid-grade (89), then using the recommended fuel instead of substituting regular (87) can actually give a lower operating cost even though the cost of the fuel is higher. If you have a car that calls for 87, then use 87 because 89 or 91/93 won't do anything. You can run a couple of tanks on the same route that you normally take and see if there is an improvement, but the engineers say there should be none. If you have a commute that takes you on the same route day after day, then run 3 or 4 tanks of 89 or 91 and see what mileage you get. If the improvement is better than 1 mpg, the math says the higher grade gives a lower cost per mile.

If your car calls for 89 or 91 and you are running 87 and it works "just fine," then you are driving in a false economy. Guaranteed.

You are missing the point. The subject line asks why premium? You, among others, said that regular is okay. Yes, it is okay because of the knock sensors, but the economy is false. I have shown the math that says using the recommended fuel instead of using regular is actually cheaper. YOU wentn off on a tangent about variable valve timing and feeling that different gas helps at idle. Whatever, if gas works better at idle, it is the knock sensors that are not retarding the timing because knock is detected with the cheap gas.

Use the good gas, not regular. The cost per mile should be lower with good gas as opposed to regular gas.

You are wrong in attributing any difference at idle to the variable valve timing. It's all from the changes to the ignition timing that is advanced with the good gas as compared to the regular. If the car calls for premium and you use regular, then the ignition timing is retarded. When you go back to premium or mid-grade, the ignition timing advances and you might feel this. The variable valve timing is not in play because the gasoline changes.

I agree with you on this point, good gas is premium as opposed to regular. Yes, better gas might be across the street at Shell or Chevron, but premium is good gas compared to regular at the same station. Regular across the street might be better than the regular at the Cheap Street station, but premium at the Cheap Street is better than regular at the Cheap Street, therefore premium is the good gas.

I accept that position, and use it myself.

You have some misinformation that I am trying to correct, and the illustration that helps explain where your train jumps the rails includes the numbers. You are right, but not for the reasons you think. And, your being right has a benefit -- the numbers -- that you seem to not be aware of.

On what basis do you say this?

It's higher priced, so it is obviously better :-)

BIGGER NUMBER! MOAR BETTER!

Your car might not be able to leverage all of the "good", but that's a different topic. Between n*****ts saying that gas changes the valve timing, and you bickering semantics, this is getting really tiresome.

I've made my point several times.

No, that's not a different topic.

Higher octane gas is not "good gas compared to regular at the same station". Not at ALL.

There is no such thing as octane levels defining quality of gas.

So, on what basis do you say this?

A car is specified to run gas with a certain octane level. It can accommodate a lower octane level, with knock sensors and a computer that can retard the timing to accommodate that, but it was specified by the engineers to run gas with a certain octane level.

So it will run better with the proper octane level.

That does not make the higher octane gas "good". It simply makes it "appropriate for the car".

The discussion is about appropriate fuel vs inappropriate fuel, because octane is not a measure of "power" or "goodness".

You're splitting hairs that do not make any difference to anybody but you. You are splitting hairs, and all you have are split ends.

That may well be true. My main aggravation was having two people who have never seen my car try to tell me I can't tell a difference in the idle using the two grades. I most certainly can. Wanna know how I can tell a difference? #1, the way my hood closes leaves a very slight gap in the latch or whatever. Often at idle, you notice a slight buzz of the front of the hood where it sits on the latch. I had a piece of foam crap to keep it from vibrating, but it's wore out I guess.

But it's only with idle rpm, and a certain vibration that causes a resonance of sorts. It's fairly pronounced when I'm burning regular gas. At idle, the hood latch or whatever will buzzzzzz..

If I run premium, the engine idles smoother, and the buzzzz goes away. The engine also sounds slightly tighter, with less valve noise, and generally purrs like a sewing machine. Put regular back in it, and the buzz will return after a while. That's how I can tell there is a difference. It's not my imagination as Elmo claims.

And I'm well aware of the ignition timing aspect. But... one reason I wasn't so sure it would be ignition timing retard due to knocking, was that the engine at idle is under no load, and should not be knocking. I know I've never seen an engine that was prone to knocking due to low octane, knock when at idle. It's always when under load.

But it is possible that the ECU is detecting knock under load and retaining the retarded timing for a period which lasts as long as the ECU detects the knock under load. If that were the case, it might be possible that the timing would be retarded even at idle, and not knocking.

I don't know.. I've never even checked the timing on that car, and would have to check the manual to see if it can even be manually set. I don't recall it even having a distributor, but I'd have to look at the Toyota manual which I do have in PDF format. Besides changing the oil, tranny fluid, and tires, I've never had to work on that car yet at 78k miles. It's been like a Timex so far.

He knows many people say that and yet know there is no difference in quality other than octane. He just wants to be a nit picking jackwagon.. :| I have no patience with people like that.

BTW, I just did a 900 mile road trip in that car this week to the dirt patch. I burned regular. Why? Because the price spread between the grades has been overly high due to a lot of shale oil being used as stock. It costs more to refine "good" gas out of that stuff vs higher grades of crude oil. It wasn't worth using the "good" stuff at the prices they are charging right now.