I personally run 93 octane in my 2015 RX350. However, I believe that you can run 87 octane as well.

 

Thanks for the information, please don’t mind my asking, but the curiosity got the better of me, why do you use 93 octane ? Have you modified your RX to utilize premium fuel to gain more HP ?

Sorry once again.

 

I use 93 octane on any engine that has a 10:1 compression and higher. Newer engines can compensate for lower octane even with high compression, but usually at the expense of engine performance and smoothness(retarded timing, and fuel cutoffs). However, the change is usually not that noticeable to many owners; if at all.

I do notice a change in how my 3.5 engine idles when using 87 octane and some sluggishness in acceleration. 93 octane has my engine running very smooth and it idles so smooth that would not know that it is running and my engine has 180k miles on the clock.

 

I've used 87 ever since the dealer told me it was the exact same engine used in Toyotas, just with a higher octane recommendation and 5hp increase, as the higher octane allows more timing adjustment as it fights detonation better. Then in 2012, Lexus dropped down to the same 87/270hp as the Toyotas, with no changes. I've managed to get by without the 5hp.

I'm at 235,000 miles, so approaching $4,500 saved, which Edmunds says it about the current trade-in value. Even blowing the engine now and getting $1000 as a junker. I'm still ahead.

 

The 275hp is with 91 octane. 93 octane rating is more like 280hp, however still not much of a gain over the 270 rating with 87 octane. I just use 93 because the engine runs better overall with it in my opinion. However, the engine runs fine with either 87, 91 or 93 octane. It all comes down to personal choice on what octane to use. A few more dollars at the pump for 93 octane do not mean much to me, but it may matter to some other owner.

 

I only usually use 93 when in the US as price difference between the grades are minimal. C$0.30/litter is the difference between 87 and 91 here up North.

 

this is from the Lexus web page:
https://support.lexus.com/s/article/...rade-shou-8129
all years and models are listed.
starting with the 2012 model all rx 350 use 87. hybrids need 91

 

The website link states that the RX350 can use 87 as the "minimal"octane needed to run the engine; not as the "preferred" octane of 91 or higher. When is the minimum required anything ever better than the higher quality stuff?

Most people seem to glaze over the "87 or higher octane" printed in the owners manuals for many late model engines as to mean the engine runs it best on 87 octane. 87 octane is the bare minimum octane needed for the engine to run; hence the "or higher "octane or better performance with 91 or higher octane.

 

So I just bought a 2011 RX350 and I have to say this Octane and the oil discussion is messed up. Holy crap. Same engine, different countries or different model (e.g. highlander vs RX350) and different recommendations. So Toyota is putting a different 2GR-FE engine in a 20** Highlander vs a RX350?

OR, maybe the RX and other ECM can adjust timing to use 93 octane - would love to know how - does it keep advancing timing until you get knocking? Because if you are running a timing based on 87 and then just change the fuel to 93, there is no way of telling - they will burn exactly the same.

I know of no other car company/engine that will run any different on a higher octane than the engine is designed for without a re-tune. So the chart posted implies that they changed the tune on the various models - e.g. 2011 RX350 is tuned to 91 and the next year they 'de-tuned' to 87. I mean it is possible. I guess.

Personally I smell a big fat load of BS. When there is a bunch of info that really just doesn't form a coherent picture something is BS.

 

Calm down.

Modern engines parameters can be adjusted by the ECU in regards to fuel octane. The ECU just monitor the knock sensor data and retard/advance timing based off engine knock in regards to octane level of the fuel. If an RX350 is using 87 octane it will knock more than if the engine was using 93 octane and will retard the engine timing until the knocking is reduced to safe level.

Toyota probably just re-tuned the ECU to allow for more knock latitude in the later 3.5 V6 RX350 models when 87 octane was allowed to be used. However due to SAE J1349 guidelines the listed horsepower of a model must be what it makes with the lowest recommended octane such as 87 hence the reduced horsepower rating. Some automakers list two different horsepower ratings for 87 and 91 octane fuels in their engines.

Nothing nefarious is happening other than some engine ECU tweaking and SAE horsepower rating changed based on the lower recommended 87 octane fuel level.

 

When the marketing department has more sway than engineering I get wound up.

 

87 costco