Octane 87 Gas Perfect For My Rx!

[huylanalexus]

Hello all,

I just had noted that Octane 87 help the transmission shift smoothly. I have a problem with the lag time in low speed; the transmission seems to slip into about 2 second of Neutral. This just happen when I put Octane 89 or Premium 93.

It sound like did make any sense that the cheap gas run smoothly than good gas.

Is there any body has the same situation? I have an appointment with dealer for checking ECM CALIBRATION SHIFTING ENHANCEMENT.

I would like to have you recommend in this case. Thanks a lot in advance.

[LEXIRX330]

Hello all,

I just had noted that Octane 87 help the transmission shift smoothly. I have a problem with the lag time in low speed; the transmission seems to slip into about 2 second of Neutral. This just happen when I put Octane 89 or Premium 93.

It sound like did make any sense that the cheap gas run smoothly than good gas.

Is there any body has the same situation? I have an appointment with dealer for checking ECM CALIBRATION SHIFTING ENHANCEMENT.

I would like to have you recommend in this case. Thanks a lot in advance.

I think that it is your imagination! I use 87 all of the time and I have tried 91 and 93 before...I have never noticed any difference and can not see how it would make any difference in how the car shifts gears???

But if it works for you keep putting it in! :D

[Kutten]

I have to agree with Lexirx330 that I never noticed any difference using 87, 89, 91; Otherthan the price :)

[Rx330driver]

i have not even tried using 87 octane in my car...but when i switched to 89, i didnt see any difference from 91...but i keep 91 in my car

[arens]

Considering the RX330 has a dual octane tune there could be an issue with his ECM or programming.

I don't know what the differences are between the 87 and 91+ octane settings are as my wife only runs 93 octane in hers. It is very likely there is a difference in shift firmness and shift points between the two octane settings.

Definately get this to the dealer and have it checked. Could be as simple as an ECM reflash to get this fixed.

[Rx330driver]

well regardless of grade of gas, the rx is known to have the weird transmission jolt if you will. we dont even get 93 octane...but you must get an extra pony or two!

[bciesq]

With a normal car (i.e., drive by cable, knock sensor, computer-less automatic transmission), the lower octane gas would result in the knock sensor retarding timing a little, which would lead to slightly lower power and torque, which could affect the automatic transmission shift points via the torque converter.

Whether/how/to what extent the RX's drive by wire computer, electronic ignition computer and transmission computer all "talk" to each other is beyond me, but in theory lower octane gas could change the shifting of the RX as well.

Personally I would rather use premium, get the re-flash and learn how to modulate the drive by wire system so that it shifts smoothy, but that's just me. If you want to save some money at the pump and the car shifts smoother (for whatever reason), go for it.

[anthonyiez]

my wife started running 87 in our highlander and i noticed a difference right away. lack of performance when under hard acceleration and a slight bit of pinging.

yes, todays cars, actually going back about 25 years now, have knock sensors which control knocking, thus protecting the engine. pinging is a different story.

[huylanalexus]

Believe me or not, after I used 4 tanks of 89, 3 of 93 and 2 of 87 that I’m very sure 87 octanes giving me a better transmission shift in low speed. This is not my imagination! I had agreed with some of you the premium 93 giving better performance compare to 87. (You can easily note if you drive a lot of local road and many traffic lights). I’m going tell Lexus dealer tomorrow to see what they can check.

Thanks all for your post.

[backwoods lex]

Funny, for me it is the opposite. My car shifts better with premium. I think it is because the higher octane provides more power. The transmission typically shifts more smoothly when the RPM's are lower. When I use 87, the gears wind out more to meet the requirements of my foot on the pedal, thus the harsher shifts. I thought I was crazy at first until I actually thought about it.

Anthonyiez, I used to get the pinging with 87 until I seafoamed the engine. I did 2 treatments and now I can save $$$ by buying the 87.

[jgr7]

All I've ever used is 87 no ping plenty of power shifts as smooth as silk.

Jeff

[chimchim]

With a normal car (i.e., drive by cable, knock sensor, computer-less automatic transmission), the lower octane gas would result in the knock sensor retarding timing a little, which would lead to slightly lower power and torque, which could affect the automatic transmission shift points via the torque converter.

Whether/how/to what extent the RX's drive by wire computer, electronic ignition computer and transmission computer all "talk" to each other is beyond me, but in theory lower octane gas could change the shifting of the RX as well.

Personally I would rather use premium, get the re-flash and learn how to modulate the drive by wire system so that it shifts smoothy, but that's just me. If you want to save some money at the pump and the car shifts smoother (for whatever reason), go for it.

+1.

bciesq seems to be the only one who knows how different octanes are used.

It's my guess as well that the knock protection mechanism of retarding timing (etc) which reduces torque/power would have the side effect of "smoothing" the transmission. It's smooth because it's like babying the accelerator more than normal.

I got the reflash and the jolt, while reduced, is still there, is still annoying, and I can't stand it.

[Boyd]

I don't really know what the fuss is about. Where I live, in S.CA the difference between regular and high octane only amounts to about $100 per year based on 15,000 miles! So, why not stick with what the factory says, high octane?

[huylanalexus]

I checked with dealer about the transmission shift in low speed, After they ran my car and other car for comparison . They 're not recommend me to do software update. They ask me to use 93 octaine to get better performance but i have to live with this problem. THey said it seems the transmission shift almost perfect from 10mph up, so that they want to do it because the update can not uninstalled.

I'm living in the city that i drive in low speed almost all the time. HOW CAN I LIVE WITH PROBLEM UNTIL 100K on this car??? I can pay for premium gas but can't pay 35K Lexus for bad performace. I'm going to check a couple about this issue and go back to dealer again very soon.

Can you please help with your suggestion?

Thanks

Believe me or not, after I used 4 tanks of 89, 3 of 93 and 2 of 87 that I’m very sure 87 octanes giving me a better transmission shift in low speed. This is not my imagination! I had agreed with some of you the premium 93 giving better performance compare to 87. (You can easily note if you drive a lot of local road and many traffic lights). I’m going tell Lexus dealer tomorrow to see what they can check.

Thanks all for your post.

I checked with dealer about the transmission shift in low speed, After they ran my car and other car for comparison . They 're not recommend me to do software update. They ask me to use 93 octaine to get better performance but i have to live with this problem. THey said it seems the transmission shift almost perfect from 10mph up, so that they want to do it because the update can not uninstalled.

I'm living in the city that i drive in low speed almost all the time. HOW CAN I LIVE WITH PROBLEM UNTIL 100K on this car??? I can pay for premium gas but can't pay 35K Lexus for bad performace. I'm going to check a couple about this issue and go back to dealer again very soon.

Can you please help with your suggestion?

Thanks

[Topshelf]

If you guys think running higher octane is going to give you more hp and/or better mileage, you should really do some research on gasoline and octane ratings. The only thing you're doing is wasting money and making the oil company's richer. Most people I explain this to reluctantly try a tankful of the 87 or the manufactures recommended minimum and come back a week later saying they can't believe how much better the vehicle runs and how much money they are going to save. I'm not going to go into all the details, but honestly, you're only fooling yourself if you think it's better for the truck. Unless you're using racing fuel which is a completely different animal, use the lowest octane you can for the best results.

[bciesq]

If you guys think running higher octane is going to give you more hp and/or better mileage, you should really do some research on gasoline and octane ratings. The only thing you're doing is wasting money and making the oil company's richer. Most people I explain this to reluctantly try a tankful of the 87 or the manufactures recommended minimum and come back a week later saying they can't believe how much better the vehicle runs and how much money they are going to save. I'm not going to go into all the details, but honestly, you're only fooling yourself if you think it's better for the truck. Unless you're using racing fuel which is a completely different animal, use the lowest octane you can for the best results.

If you get a chance, I would appreciate it if you would go into all the details. (honestly, I'm not trying to be snarky)

My understanding is that octane relates to how much gasoline can be compressed before it spontaneously ignites -- the higher the octane the more compression before pre-ignition. Higher octane fuel does not contain more energy, but rather it can be ignited under "better" circumstances, i.e., higher compression.*

In my old '73 VW Thing, I use 87 octane because the motor only has a 7:1 compression ratio. The RX330 has a 10.8:1 compression ratio which tells me that it was designed to run higher octane (by way of comparison, the RX300 ran 10.5:1; new Corvettes run 11:1, 350Zs run 10.3:1, Mustang GTs 9.8:1).

If I use 87 octane the RX's knock sensor will compensate for the lower octane by retarding timing, and as a result the engine will run fine (i.e., won't damage the engine), but unless the laws of physics have been suspended inside the combustion chamber of the RX, retarding timing at a given compression ratio will result in less power. (OK, that was a little snarky, my apologies).

Bottom line: if a high compression engine runs better with lower octane gas, then something is wrong with the car (either software wise or mechanically).

I'll give Cecil from The Straight Dope the last word. Money quote:

Occasionally you get some genius who takes the opposite tack--he spends an extra 10 or 20 grand buying a high-performance car, then decides he's going to save three bucks per tankful using regular instead of premium as specified. He figures as long as the engine doesn't knock he's OK. Wrong, carbon monoxide brain. Car engines nowadays contain knock sensors that detect detonation and automatically !Removed! the spark to compensate. The delay means maximum gas expansion occurs when the piston is farther along in its downstroke and thus there's more room in the cylinder head. This reduces peak cylinder pressure, eliminating knock but also giving you less power and poorer mileage.

* Many engines perform fine at lower compression if that is how they were designed.

[Topshelf]

I do agree that buying a high performance car, or any car that requires 91+ octane, and using 87 octane is a complete act of stupidity. My C230 requires 91, so I'm stuck using 93 as that is the lowest octane I can get around here without going below the manufacturers recommended minimum. However, a knock sensor is not a performance mod. It's a safety feature to make sure the fuel doesn't prematurely detonate due to bad gas or too low of an octane. To get the benefits of higher octane, you have to remap the ecu, or use an aftermarket tool. I've been around high performance cars and motorcycles for years, so it's not like I just made this up. Yes, you might see the slighest of tiny increases, but most of it is a placebo effect. Some people think that simply putting more expensive gas in their vehicle will add all kinds of performance benefits and better gas milage. Meanwhile, these vehicles have very complicated fuel maps setup by engineers using a specific octane level for the best compromise of performance/economy. Sure, have your maps redone for premium fuel, then I'll buy the benefits. But in a stock luxury suv???

[bciesq]

I do agree that buying a high performance car, or any car that requires 91+ octane, and using 87 octane is a complete act of stupidity. My C230 requires 91, so I'm stuck using 93 as that is the lowest octane I can get around here without going below the manufacturers recommended minimum. However, a knock sensor is not a performance mod. It's a safety feature to make sure the fuel doesn't prematurely detonate due to bad gas or too low of an octane. To get the benefits of higher octane, you have to remap the ecu, or use an aftermarket tool. I've been around high performance cars and motorcycles for years, so it's not like I just made this up. Yes, you might see the slighest of tiny increases, but most of it is a placebo effect. Some people think that simply putting more expensive gas in their vehicle will add all kinds of performance benefits and better gas milage. Meanwhile, these vehicles have very complicated fuel maps setup by engineers using a specific octane level for the best compromise of performance/economy. Sure, have your maps redone for premium fuel, then I'll buy the benefits. But in a stock luxury suv???

In general I don't disagree with you, but when I see the high compression ratio on this car and the fact that a 3.3L V6 is having to move 5500 lbs, then I err on the side of treating it like a high performance engine.

I've also had ECU's remapped on my turbo VWs so I understand that not all cars are designed to take advantage of high octane gas, but when I read this:

Select Octane Rating 87 (Research Octane Number 91) or

higher. For improved vehicle performance, the use of

premium unleaded gasoline with an Octane Rating 91

(Research Octane Number 96) or higher is recommended.

it makes me wonder if the car doesn't have fuel maps for higher octane gas but will operate fine on lower octane via the knock sensor.

I appreciate your measured response since I was a little snarky before, but I still wonder what octane rating is incorporated in the RX330 fuel maps.

[Topshelf]

Haha, it was a little snarky, but I expected much worse. :D Hey, if anyone believes their truck runs better using 93, then enjoy. I'm just not going to buy into it. I would love to see a dyno comparo done the same day using 87 and then 93. That would be interesting! That being said, the above quote is intriguing. Maybe I'll throw a tank of 93 in since I'm almost empty and see if my mileage increases. I would need to see an increase of 1.5 mpg to justify the added expense of premium fuel. I'm not expecting to get that kind of result, but I'm up for an experiment.

Just noticed that you own a 330. Is that quote also listed for the 300?

Edit: Yep, also listed for the 300. I'll fill up tomorrow with 93 and see what happens. I actually need to gain 2.25 mpg to justify premium. I thought it was $.20 more, but it's $.30/gallon more than 87.

[Ericok]

So the bottom line is that Lexus (which designs and builds the car)recommends the use of premium gas just for the hell of it?

[bciesq]

So the bottom line is that Lexus (which designs and builds the car)recommends the use of premium gas just for the hell of it?

Until someone either does back to back dynos on the same car or we get someone with knowledge of the stock fuel maps, we just won't know for sure.

In the mean time, I'm using premium just be safe for the reasons I stated above.

[Topshelf]

So the bottom line is that Lexus (which designs and builds the car)recommends the use of premium gas just for the hell of it?

No, Lexus recommends 87. But since the car companies and oil companies are tied together, they "suggest" that using a more expensive fuel, may give you improved performance.;)

[Boyd]

Not to beat a dead horsepower, no pun intended. Do the math on my previous post. Let's say you get 24 miles per gallon. Divide 15,000 miles by 24 miles per gallon and you get the gasoline required for 15,000 miles, you would burn 625 gallons. Where I live the premium is 20 cents more than regular. Hence, 625 gallons times 20 cents = $125.00 per year. Is it worth the savings to disregard the manufacturer's recommended fuel? Do you think they're getting a kickback from the oil companies? There has to be a good reason.

Boyd

[Topshelf]

24mpg!?!?!?! If that's what using premium gets me, I won't say another word. I average 18mpg. Using your calculations and $.30/gal increase for premium, I'm looking at $250 extra over the course of a year. And for what? To think I'm doing myself a favor? Unless someone can show me proof of either an considerable increase in performance, or mileage, then I'm doing myself a bigger favor by putting that $250 in my pocket. Running 87 will not harm your engine in any way. So don't think that using 93 is going to make it last longer. That being said, I'm filling up with 93 tomorrow to start my first test. And keep in mind that this test will be taking place under ideal weather conditions...Little to no need for AC and no need to idle the truck to warm it up in the morning. We'll see, but I'm not expecting much.

And lastly, the manufacturers recommended fuel is 87!

[LEXIRX330]

Is it worth the savings to disregard the manufacturer's recommended fuel?

Boyd

How are you disregarding what the manufacturer recommends by using 87? I have run super, plus, and reg never noticed a difference in MPG or anything else...it has nothing to do with the $125.00 :whistles: why put super in it if you do not need to? And if you do not see any benefit from it...is 87 going to mess up my RX? If so why do they tell you that you can use it?

I totally agree about the c230...but it says that you have to use premium...91 or higher not 87 or higher....

24mpg!?!?!?! If that's what using premium gets me, I won't say another word. I average 18mpg. Using your calculations and $.30/gal increase for premium, I'm looking at $250 extra over the course of a year. And for what? To think I'm doing myself a favor? Unless someone can show me proof of either an considerable increase in performance, or mileage, then I'm doing myself a bigger favor by putting that $250 in my pocket. Running 87 will not harm your engine in any way. So don't think that using 93 is going to make it last longer. That being said, I'm filling up with 93 tomorrow to start my first test. And keep in mind that this test will be taking place under ideal weather conditions...Little to no need for AC and no need to idle the truck to warm it up in the morning. We'll see, but I'm not expecting much.

And lastly, the manufacturers recommended fuel is 87!

I have AWD and I average 21 - 24 using reg! I agree with you...