Running Regular Gasoline

[Chas Martel]

I have a 2021 RX450h. Owned it for 13 months now and am very happy with the vehicle and plan to keep it long term. I've discovered that I get a little bit better gas milage running regular grade gasoline through it than using factory recommended premium fuel. Haven't noticed any engine pinging. Why shouldn't I continue to run regular fuel?

[Les Lex 2018]

I'm not surprised that the RX is not pinging, due the fact hat you have an infinite number of gears, based on the speed of the electric motor-generator between the wheels and the engine, with the computer controlling the load on the engine.

My guess would be that Lexus wants to ensure that you aren't getting the vehicle into a set of parameters that will cause pinging.

Say you have to commute thru the mountains, and you are climbing a steep grade and playing with the paddle shifters.  Can you force the system into a gear ratio that will lug the engine, and therefore cause it to ping?  It's possible!  If the RX is running great on Regular, you, theoretically, are not pushing the envelop.  And that's a good thing.

[Olygirl]

I also have a 2021  RX45OH. I was told by two Lexus service centers that although the vehicle would probably run okay,  using regular unleaded instead of premium would invalidate the warranty if there is an issue with the engine.

Edited April 7, 2023 by Olygirl

[Zeus253]

I agree with "Olygirl", if you're still under warranty or sven slightly out of warranty then best to not use regular. The cost difference isn't worth the risks. Almost seems the same as saying lower grade oil is ok to use all the time. In a hardship, it won't completely destroy but regular use of fluids not recommended is never a good idea. Full disclosure just my opinion based on learning the hard way. Hope the best for you. 

[Chas Martel]

Hey Zues253, I'm interested to hear the details of the episode you experienced that led you to state, "base on learning the hard way,"

[Les Lex 2018]

According to Chas, Premium fuel is recommended.  There is a difference between the terms recommended and required. Check your OM to see if that's true.

On the other hand: The correct oil for the RX is "required", not simply a recommendation.  Failure to use the correct oil will start to damaging the engine quickly. There is one exception to that if you switch back to the required oil.

If you can sleep like a baby knowing you put the most expensive, best gasoline you can find in your RX, then it's dang well worth it.

On the other hand: If you drive like grandpa Jones and you simply drive to stay alive, I seriously doubt that you are going to damage your engine running regular.

TMC uses sophisticated and expensive timing-advance hardware built into the RX to handle engine knock/pinging. But it won't save an engine that is abused by hard driving while using non-recommended fuel.

[Carbuff2]

Just acquired a 2023 RX500h F-Sport...

 

Below are the octane requirements (USA ratings).

 

MINIMUM RX350H = 87 octane

MINIMUM RX500H = 91 octane

Edited May 15, 2023 by Carbuff2

[RX400h]

So for the RX350h, 91 octane or higher is recommended, but 87 is considered to be the minimum value.

The RX500h requires a minimum octane of 91, which is the highest octane in CA and some other states like Arizona.

The AKI numbers given by auto manufacturers is the average of the Research Octane Number (RON) and the Motor Octane Number (MON)which is (R+M)/2

[Cra cra]

I bought a SC 430 this past week. I am very happy with it. Beautiful condition. A little.over 75,000. Had to replace the battery right away. The VSC off light on the dash came on and pushing the button doesn’t turn it on. Could changing the battery cause this? How can I reset it.

[THX919]

What are your thoughts on the 2023 RX 350 F Sport, which has the same engine as the plan RX 350. Would putting an 87 octane fuel for the RX 350 with the 2.4L Turbo be ok? 

[Carbuff2]

 

13 hours ago, THX919 said:

What are your thoughts on the 2023 RX 350 F Sport, which has the same engine as the plan RX 350. Would putting an 87 octane fuel for the RX 350 with the 2.4L Turbo be ok? 

Again, look at the owners manual recommendation...SPECIFICATIONS  pg 579, section 8-1.

 

I'm sure that Lexus builds a bit of leeway into the recommendations...A turbo engine might need extra protection due to spooling characteristics.

 

A higher octane suggestion might only be because they expect owners of F-Sport models to drive more 'enthusiastically'.😅