Fuel Octane

[ROBKOWSKI]

I have a 2008 RX 400h.  I been using 93 octane fuel since I bought it used at 50 K miles like the owner manual state should be used. I average 24.5 MPG.  Today I put in 89 octane Shell gasoline.  My wife was upset with me but I am tired of paying for premium 93 octane. I know one tank is not going to hurt anything.  What are you all using and what's your experience?  Thank you.

[RX400h]

Our 2006 RX400h is now 18 years old and I've ALWAYS used 89 octane (mid grade) fuel. I interpreted the owners manual as saying that 89 is perfectly acceptable, and it has been. Our average MPG is about the same as yours. 
I do suspect that higher octane may be beneficial when the ambient temperature is very high. Since we live within 10 miles of the coast, the temps here are rarely over 80 degrees F.

[Naval Air]

For several years on 3 different Lexi I blended 2/3 (93) with 1/3 (87) to yield the (91) recommended octane. Since Biden I have changed to 50% (93) and 50% (87) to yield (90) octane and have noted no Milne or performance issues. Interestingly (90) octane is highest octane rating in Alaska.

 

 

[ROBKOWSKI]

Thanks for your comments.  I might give it a try.  

[Julie J]

On 4/11/2023 at 7:25 PM, ROBKOWSKI said:

I have a 2008 RX 400h.  I been using 93 octane fuel since I bought it used at 50 K miles like the owner manual state should be used. I average 24.5 MPG.  Today I put in 89 octane Shell gasoline.  My wife was upset with me but I am tired of paying for premium 93 octane. I know one tank is not going to hurt anything.  What are you all using and what's your experience?  Thank you.

I have never used the premium & my Lexus has run fine for years.