carguy75

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

Abrar

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.

carguy75

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.

RichS

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.

carguy75

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.

lex_rx

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.

cwaggs

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

carguy75

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.