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Toyota Service
Toyota Service, Lexus and Toyota expert
Category: Lexus
Satisfied Customers: 4821
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Do I really need to use premium gas in my 2000 ES300 Lexus.

Customer Question

Hi, Do I really need to use premium gas in my 2000 ES300 Lexus. If so, why? Thanks, Marie
Submitted: 1 year ago.
Category: Lexus
Expert:  Toyota Service replied 1 year ago.

Hello. Welcome to Just Answer. Please allow me to assist you. Before we begin, who told you, or where did you read that you need to use premium fuel? Thanks

Customer: replied 1 year ago.
The owner's manual for the car
Expert:  Toyota Service replied 1 year ago.

This engine has some rather sensitive knock sensors. Lower octane gas could allow detonation ("Knock"), which premium gas prevents; this is why they recommend premium. If you do not want to incur the higher expense of premium, you could try using 89 octane gas. However, the check engine light may come on and you will have a knock sensor code stored in the car's computer. If this occurs, you would want to return to premium fuel. On a related note, this engine (minus a bit of tuning) is the exact same engine used in the Toyota product line. Interestingly, Toyota does not require premium. On my car, I use 89 all the time and I have no issues. I also get 30 mpg. Depending on where you live, the quality of the fuel, the elevation, and ambient temperatures all contribute to whether or not premium is absolutely necessary. I would recommend you move down to 89 and see if you get any knock or check engine light illumination. Please be advised your mileage may drop a bit though.

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Customer: replied 1 year ago.
What's knock? Will I damage the car by using regular gas?
Expert:  Toyota Service replied 1 year ago.

"Knock", or, in automotive terms, "Preignition" or 'pre-detonation"is where the fuel mixture combusts at the improper time. If you have ever driven an older car, with a carburetor, and heard a rattle on acceleration (like metal balls rattling in a tin can), that is knock. Older cars had no knock sensors to reduce this.The knock sensors are in place to reduce this phenomenon. Again, in automotive terms, the knock sensors detect the condition as it starts to happen, and the instant the spark happens is moved a few milliseconds. Knock will not hurt the engine, but you will see a loss of power and mileage if and when it happens. I would say that if you drive mostly on flat roads, with no elevation changes, you may never hear or see knock on 89 octane gas. If you live in a hilly area where you need to go up in elevation, stay with premium