Hi Scotty! I just purchased a 2019 Lexus GX460 with 52,249 miles on it, and I love it. I have fallen down the rabbit hole regarding whether or not I have to use premium gas. After countless forums, articles, and YouTube videos I’ve come to you for (hopefully) a definitive answer, as I’ve found a lot of info on both sides of this discussion. I am not auto-mechanically inclined so don’t know enough to form a good basis for judgement. I’m happy to put premium in this vehicle if necessary as I’d like to keep it a long, long time and have it continue to run well, and I’m nervous I’ll damage the engine using 87 instead of 93. However, 93 is $0.80 more/gallon currently and I’d like to not spend that money if I don’t have to. Best I’ve been able to understand (in a very simplistic way) is the engine was designed to achieve maximum performance using 91 or better fuel, but the computer will adjust if 87 is used and there may just be some reduction in overall engine power output and/or mpg. Is that correct? I’m more concerned with potential for long term damage to the engine using 87 only. I also read on a forum somewhere that using a half bottle of Techron or VP Racing fuel system cleaner every 5,000 miles (if using 87 gas consistently) will help prevent carbon build up and potential damage. Just don’t know what’s right, and want to treat this vehicle appropriately for the long run. Thanks so much for all your content and information, very helpful & entertaining!!! Take care!
we've had this question hundreds of times. Please use the search.
If you're racing your car and really need those extra few ponies, then use premium. Otherwise, don't.
Got it, thank you.
If the manual says 91 is required, use 91. In my state, there is no 93; 91 is our highest grade. If it says 91 is recommended then you can use 87.
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I don’t understand why people buy luxury cars but balk at having to pay premium gas. Luxury cars tend to cost more in terms of ownership than non-luxury cars; it comes with the territory. Also, it’s a good idea to have researched which gas to put in before you bought the vehicle.
Thank you for the reply. As I said I'm totally willing to use premium, and I agree that reality is the cost of ownership for a luxury car will be higher, I'm comfortable with that. I'm curious as to the validity from a mechanical standpoint. Frankly, I was surprised to see so much varying opinion on both sides of the question.
but it usually says something like "required for best performance" , which means it's not really required.
I have not seen "required for best performance" in manuals. When I was shopping for a Lexus GS it said "Premium gasoline required". My 2000 Acura Integra's manual says "Premium gasoline required". Nothing was mentioned about "for best performance".
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OP will have to read his manual and see what it says.
I've seen it countless times in the course of looking up people's manuals for them on this forum.
Here is a Lexus IS:
Lexus GS
On page 570 of the owner's manual for a 2019 Lexus GX460 there's no mention of "required or recommended", simply states use "91 octane or higher". link: https://ownersman.com/manuals/2019-Lexus-Gx460-owners-manual
@hixster 8 pages later: 91 (Research Octane Number 96) or higher required for optimum engine performance and fuel economy.
you guys need to pay more attention to what Scotty says.
Thx @mmj , required = must use premium.
"... for optimum engine performance and fuel economy."
Just like Scotty says, over and over.
Thank you MMJ. I stand corrected.
Scotty has stated (many) times "the car's computer can compensate". The lone caveat being the car not having a high performance or high compression engine. Or as is in this case, premium is not required, got it.
Guys, my apologies for beating the dead horse, but to dumb it down so I'm clear.
"Premium required for optimum engine performance and fuel economy" = 93 (or 91) is best for car/engine/ECU design on this vehicle, but 87 will not cause engine damage (if I'm hearing Scotty right in the video) just might lose some HP and MPG efficiency.
Thanks again to all for the help.
Apologies for any confusion. Yes, you can use regular unleaded. Scotty states this definitively in the first minute of the video posted above by @mmj
@hixster @mmj @daywalker Thank you all
I was surprised to see so much varying opinion on both sides of the question.
Don’t overthink it. What does the manual say? Go off of that.
Thank you
I am not auto-mechanically inclined so don’t know enough to form a good basis for judgement.
No worries. See the owner's manual, which type of gasoline to buy is in there.
I just came across the FAQ section with a link to a video where Scotty answers this question about a different car. Sorry if this was outside the guidelines for the forum. Seems like the answer is 87 will not harm the engine because of the computers ability to adjust for the grade of fuel. Thanks for the reply Justin!!
Sorry if this was outside the guidelines for the forum
you're not breaking rules, but if you want an answer to a common question, then chances are it has already been answered. So, use the search first and check the FAQ.
The way luxury and premium cars get a little more performance is by using higher octane gas.
Like @daywalker said above, the keywords are in the manual: required or recommended.
Thank you!