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Hesitation problem at various speeds (TSB info post #159)

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Hesitation problem at various speeds (TSB info post #159)

 
Old 05-14-19, 02:18 AM
  #1006  
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Originally Posted by coolsaber View Post
https://lexus2.custhelp.com/app/answ...xus-vehicle%3F

RecommendedMinimumOctane Rating: 87 350/91 450h



Use of unleaded gasoline with an octane rating lower than what is listed for your model year vehicle may result in engine knocking.
If the octane rating used is less than required, damage to the engine may occur and may void the vehicle warranty.


Yep, and the official US Dept. of Energy Fuel Economy Tests are done with Regular gas for the RX 350 and Premium Gas for the RX 450h

https://www.fueleconomy.gov/feg/Powe...RX&srchtyp=ymm
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rxtimes2 (05-14-19)
Old 05-14-19, 09:11 AM
  #1007  
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Originally Posted by coolsaber View Post
https://lexus2.custhelp.com/app/answ...xus-vehicle%3F

RecommendedMinimumOctane Rating: 87 350/91 450h
Use of unleaded gasoline with an octane rating lower than what is listed for your model year vehicle may result in engine knocking.
If the octane rating used is less than required, damage to the engine may occur and may void the vehicle warranty.
There is confusion; in that doc that you provide the link for it does say recommended, but this is what's in my owner's manual:

Select octane rating 87 (Research Octane Number 91) or higher. Use of unleaded gasoline with an octane rating lower than 87 may result in engine knocking. Persistent knocking can lead to engine damage.



This is NOT a recommendation, but a warning not to go below 87. I imagine that if one goes below 87 the computer could not compensate.



So here we have two documents saying the same thing, but with different meanings. In the end one does what one think it's best.


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coolsaber (05-15-19)
Old 05-15-19, 06:41 AM
  #1008  
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In agreement. The computer is designed to run from 87+ in the 350, so unless you put in diesel (happens to the best of us) or live in a high alt climate (I have heard Denver gets 85 seasonally?) no really way to go wrong with any tier of gasoline widely available.

Now the bigger question is most engineers on interviews have written about power numbers, and octane the vehicle was designed for; vehicles performance is best suited with the octane number the engineers designed the motor to run with, and you are wasting money by pumping in more expensive or cheaper gas. With Lexus stating anything 87 and above, which did they use? Its cut and dry for other vehicles like the GX or even LX where they specify a single octane (the motors are used in other vehicles where they are spec`d for lower octane and have different power numbers). The same motor in the RX is used elsewhere where 87 is the go to.
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Old 05-15-19, 08:42 AM
  #1009  
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Originally Posted by coolsaber View Post
Now the bigger question is most engineers on interviews have written about power numbers, and octane the vehicle was designed for; vehicles performance is best suited with the octane number the engineers designed the motor to run with, and you are wasting money by pumping in more expensive or cheaper gas. With Lexus stating anything 87 and above, which did they use?.
Great question !!! I did not do this, but a forum poster, quite a few months ago, said that he did contact Lexus and they told him that all tests were done with 91 octane. I believe that was from Lexus Canada, am not certain.
I can't remember his name nor the date or subject heading alas. I tend to believe this as in every other country the recommended octane is 91 minimum.
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Old 05-16-19, 06:29 AM
  #1010  
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Originally Posted by Cocal View Post
Great question !!! I did not do this, but a forum poster, quite a few months ago, said that he did contact Lexus and they told him that all tests were done with 91 octane. I believe that was from Lexus Canada, am not certain.
I can't remember his name nor the date or subject heading alas. I tend to believe this as in every other country the recommended octane is 91 minimum.
Over the years, there have been many posters on here that claimed to have called car manufacturers, tire companies etc, and have gotten conflicting answers. I believe they didn't reach the right people and are just given any answer they think you want to hear. JMHO.
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Old 05-16-19, 07:43 AM
  #1011  
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Originally Posted by ravenuer View Post
Over the years, there have been many posters on here that claimed to have called car manufacturers, tire companies etc, and have gotten conflicting answers. I believe they didn't reach the right people and are just given any answer they think you want to hear. JMHO.
The only reason why I do give credence to that poster is that elsewhere in the world they use 91. Here in North America they dumb-down all maintenance to a non optimal level, that applies to all makes.
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Old 05-16-19, 08:01 AM
  #1012  
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https://www.economist.com/babbage/20...-needs-premium


In Europe, the octane rating on the pump is simply the RON figure. America, by contrast, uses the average of the RON and the MON figures, called the AKI (anti-knock index). Thus, 97 octane “super unleaded” in Britain is roughly equivalent to 91 octane premium in the United States.
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