Oldfart

Yes, but our regular in SoCal is $3.40

Elation

Where does it say there is no performance advantage using a higher octane.
The manual doesn't say.

Does it recommend 87 but can use 91?
Does it recommend 91 but can use 87?
The manual doesn't state.
I want to believe that the RX 350's engine is engineer to accept 87, but nobody can prove that, hence this thread exists.

This what 2017 Ford Mustang manual says.

Oldfart

Lexus manual is very clear.
For RX350 it states use 87, what is unclear about it?

Elation

Does it recommend 87 but can use 91?
Does it recommend 91 but can use 87?
The manual doesn't state.


The government site also believes that 87 is what it recommends.
But I want to see that from my own owner's manual.
When I asked the my sales guy at the dealer, he said he'd use Premium if I wanted to keep the car for a long time.
I can't argue that he's wrong because the manual doesn't state anything other than it recommends "87 or higher".

Mike728

If you need it in writing, just grab a pen and add it yourself. I'm not sure how some people can sleep at night.

tomtom74

Then just use 91. It comes down to it's your car and your money. As simple as that.

PeeVee

My sales guy only told me to use Premium to keep the injectors clean. But then again we can use one or twice a year the injector cleaner product into a full gaz tank...

Mike728

Why, does premium contain more detergents than regular unleaded?

PeeVee

That is a good question. But that is what I was told by my salesman.

Cocal

Again it's a matter of interpretation! You read that way, I instead read it that you may not go below 87, the engine is designed for premium, but thanks to the electronics it can compensate for lower octane up to a point, the computer will retard/advance before/after Top Dead Centre (BTDC/ATDC). Now there are other benefits to premium grade which are not apparent to the average driver, especially in engines with GDI one of which is the lower amount of deposit on valve-seats and piston-heads. Now I'm not talking to people who lease or only keep a vehicle for a couple of years, these will never see the benefit of premium gas. Those like me who keep a vehicle for 5 or more years will, they'll spend less money in maintenance, it's a bit of pay a little sooner or a lot later + inconvenience. The choice is ours!

PeeVee

Go check the link to Wikipedia I sent earlier.

Premium (91) gas does not contain more energy than regular (87). Premium only contains an agent that prevents the early detonation, giving a more precise timing on the time and duration of the blast of energy. The higher octane is really more effective for engines made to run at higher RPM (like sport cars).

For engines tuned for 87, get no gain in any way from premium (see the Wikipedia link, and there are studies that demonstrates that).

Cocal

Again, where does it say that it's tuned for 87? It's tuned for 91 but you may use 87 (thanks to the computer)

kitlz

The Lexus website states the minimum octane requirements. Hopefully this should clear up any confusion.

PeeVee

If it was tuned for 91, the engine would be knocking and you would damage it.

sderman

I was under the impression that "Top Tier" designated gasoline suppliers put the same amount of detergents and other additives in all grades so the only relevant difference between the grades is octane.