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The USA uses Ron+Mon/2 = AKI

Your rule of thumb may be close but no cigar.
 

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since buying the is300 Ive tryed hard to only get 93 or higher here and there Im forced to get some regular.Then its a back to the good stuff with some treatment to clean out the gas but it sucks with the gas prices
 

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toptier link was cool..
you i know theres a difference in gas stations but i noticed that alabama gas stations are 93octane with 10% ethanol..
entec has 93.5 with 10% so thats what the IS eats..
 

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Petro Canada Over here bought Sunoco, so they have 94 octane now.

still gonna put 91 though..... Might try 94 one time and see if theres a diff
 

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question / knocking on 91

Ok so i just read this whole thread and i have a question not addressed.. I use 91 octane from a wholesale club all the time in my manual IS.. 130k miles, all services done so far.

when i am engaging gears, (and only then), i hear pinging.. (with windows open and listening for it). not while i'm accelerating, not with AC on while going up hills, only while i am letting clutch out.. then it stops pinging. (average driving, not racing).. If i engage gears extra slowly, i still hear a little knock.

All i have added under the hood is an intake.. which i may remove just to figure out if too much air is the cause. (i had a cat back exhaust once too but i don't believe anything was re-programmed by my installers)

An engine either knocks or it doesn't in my understanding, right?.. so i'm stumped besides the CAI or possibly i'm not really getting the proper octane gas that i'm paying for.. Any thoughts?
 

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This sounds off to me.

If you mean you hear pinging as u roll on the gas after changing gear ok thats probably pinging.

If you hear pinging before you roll on the gas its the clutch or gearbox.

Don't forget your ignition and mixture is computer controlled, so no you dont have "An engine either knocks or it doesn't in my understanding, right?.."

I run my IS300 on premium from shell, racetrack and costco and don't find there is any difference. No knocking at any time.

If you are older then you have had cars that knock all the time, for years and years, with no disaster. But they generally didnt last as long as engines today, and ring land wear was very noticeable at 60 to 100k miles. Replacing the pistons was generally all that was needed.

However if these were timed wrong then pistons would get punched through. Today's Knock sensors should prevent this IMHO.
 

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This sounds off to me.

If you mean you hear pinging as u roll on the gas after changing gear ok thats probably pinging.
I am older yes, this is my 5th car and the one i've kept the longest, > 5 fantastic trouble-free years.. but anyway yes what you said above is what i meant. i (fortunately) don't hear anything before i roll on the gas.

One time during my ownership of this car i used lower than premium as a test and i heard pinging constantly and noticed significant performance loss so i'm kinda confused why i'm hearing some of that pinging again lately but it is definitely only while rolling on the gas. After the clutch is fully out, i'm fine.

Could i possibly be getting lower octane gas than i am really paying for? (it's BJ's wholesale club.. i haven't seen gas from this club mentioned on here before but it's where i always go.. if i knew how to, i would test the gas).

or... if it's not an octane issue, what else could it be, since we have the those knock sensors and computer controls..

thanks for reading.
 

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After the clutch is fully out, i'm fine.
Ok this is why I am skeptical. If you are still on the clutch the engine is still relatively low load, or it is if your clutch lasts 140K like mine....

So to eliminate pinging add octane booster to a full tank and see if it goes away.

I would expect a lean condition that causes Knock to throw a code.

If it is confirmed knock after the octane booster test I would use Techron for a few tanks to see if it helps, and maybe a carbon deposit cleaner.
Then clean the MAF ?
Then injectors out and sent to service ? ?

Anyone else have comments ?
 

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I have a 02 is300. I have a problem whenever I get down to 1/4 tank I run out of gas. Can anyone give me any potential problems. I have no mods done to it
 

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Come on guys, its only like 5 more dollars for premium. Just don't spend 8 dollars at a fast food joint one day out of the week. :D
 

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Nice post! I always put shell premium in my car, only on ocassion i will use mobil. You can def see the dif when it comes to the octane rating not only in power but in gas mileage. The amount of premium gas you put in will get you farther than the same amount of 87/89 so why cheap out when it comes to your car? the difference in price is only $.20 or so and if you put 16 gallons in your car which fills my is300 from just about empty its only a $3.00 difference. If your spending $70 already why cheap out to save $3.00? just my opinion
 

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I've been putting regular unleaded in my car for a long time. I only use top tier gasoline places like shell, chevron, and QT though. I guess ill start switching it up with some premium now and then. I have never really experienced Pinging before with regular though.
 

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I've been putting regular unleaded in my car for a long time. I only use top tier gasoline places like shell, chevron, and QT though. I guess ill start switching it up with some premium now and then. I have never really experienced Pinging before with regular though.
It wont ping because the ECU has ignition retarded far enough.

That said youre losing power and efficiency (thus costing you more in fuel) by not only having a fuel that burns faster and less predictably but also because the ignition timing is so retarded that the burns dont complete with optimal timing.

If you go on a road trip that will require 2 full tanks do one on regular then reset the ECU (disconnect the battery) and then run the second on premium. I GUARANTEE a difference. Also, try to drive at a smooth maintainable pace. Try 70mph instead of 80 where you might have to slow down all the time for slower traffic and such.

I've noticed a 1-2 mpg difference with 89 octane vs my usual 91-93. I have never put more than a splash of 87 in to get me to the next station which did have premium.
 

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Ive been putting Premium in for the past couple days and have noticed the mileage getting a little better even without resetting the ECU. I drive around 40 miles a day becuase of school and work commute. Ill try filling up in the morning with Premium and resetting the ECU. I kind of wondered why my friends Civics were pwning me haha. Anyone have experience with the STP add-in injector cleaners? Might throw a couple of those in if anyone has exp. with them .
 
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