regular or premium?
Pole Position
Joined: Dec 2012
Posts: 2,149
Likes: 960
From: Toronto, ON
If you have an engine malfunciton that they deem due to engine knock from using regular gas, then warranty is void (this is paraphrased from the manual). Knock can occur when high combustion chamber pressures cause spontaneous improper ignition of fuel, premium fuel is more resistant to this. I have not used regular in mine, but I did use regular in my RX which called from premium as well. However I feel that was a different situation as while it was a high static compression engine, it was an atkinson cycle (hybrid) which means in practice lower actual combustion chamber pressures. The computer corrected for the regular gas quite well without issue. This is similar situation to why the NX350h recommends premium (high static compression engine), but does ok with regular.
Now, this is pretty much opposite situation of the T24A engine in the NX350, it has a low static compression ratio but the turbo charger of course can greatly boost the actual combustion chamber pressures. This same engine is used in the Highlander, but it has been tuned to allow use regular gas, and consequently has a lower HP rating than the NX. If you feel determined to try regular, then keep it in ECO mode and avoid full boost pressure on the turbo.
Now, this is pretty much opposite situation of the T24A engine in the NX350, it has a low static compression ratio but the turbo charger of course can greatly boost the actual combustion chamber pressures. This same engine is used in the Highlander, but it has been tuned to allow use regular gas, and consequently has a lower HP rating than the NX. If you feel determined to try regular, then keep it in ECO mode and avoid full boost pressure on the turbo.
Pit Crew
Joined: Aug 2015
Posts: 194
Likes: 60
From: Oregon
From all I've read, experienced and otherwise learned, it's best to use what the manufacturer recommends. There's no benefit to move up to premium if it's not called for, and it's risky to go down if it is. This is my first premium using car for a long time, and I understand the hurt at the pump, but I really like my car and want to protect my investment. Also, currently at 64 mpg, it doesn't hurt as much as I thought.
Instructor
Joined: Mar 2017
Posts: 856
Likes: 326
From: Illinois
From all I've read, experienced and otherwise learned, it's best to use what the manufacturer recommends. There's no benefit to move up to premium if it's not called for, and it's risky to go down if it is. This is my first premium using car for a long time, and I understand the hurt at the pump, but I really like my car and want to protect my investment. Also, currently at 64 mpg, it doesn't hurt as much as I thought.
Guest
Joined: Nov 2022
Posts: 377
Likes: 199
Premium is the manufacturer recommended fuel for the 350h. This car uses very little gas anyway so I'll use premium. I've been using it in my cars for 20 years as manufactured recommended. I follow the manufacturer guidance for oil changes, tire psi, etc. etc. They know way more than I do.
Pit Crew
Joined: Aug 2015
Posts: 194
Likes: 60
From: Oregon
Driver
Joined: Feb 2023
Posts: 78
Likes: 38
From: IL
I don’t see an “h” in your description so I will assume that you are asking about the ICE version. That version is what I have and since it says Premium, that’s what I use. Given the small tank, I understand the desire, but I’m following the Lexus guidance on this one.
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Racer
Joined: Oct 2002
Posts: 1,488
Likes: 52
From: FL
This discussion has been going on since Club Lexus has existed. Many opinions are available if you do a search.
The basics I believe are first that you use a Top Tier gasoline. Toptiergas.com
Secondly without getting into a technical discussion on engine design, I subscribe to the blend method. I try to never my gas tank get too far below half and fill up with regular then premium the next time. I have never had any issue with all 5 of my Lexus' and Toyotas over the years.
The basics I believe are first that you use a Top Tier gasoline. Toptiergas.com
Secondly without getting into a technical discussion on engine design, I subscribe to the blend method. I try to never my gas tank get too far below half and fill up with regular then premium the next time. I have never had any issue with all 5 of my Lexus' and Toyotas over the years.
Advanced
Joined: Feb 2005
Posts: 564
Likes: 162
From: Mid-West
You purchased $50K Lexus. With driving about 12K miles/year it may cost you about $350/year more in 93 gasoline vs 87. Why have lower performance and risking damaging your vehicle engine for $30/month?
Last edited by Lex2000TL; Jun 4, 2023 at 01:02 PM.
Driver School Candidate
Joined: Aug 2022
Posts: 18
Likes: 18
From: NC
Although from earlier threads looks like they may have Leased, which I guess could change the argument some if they have zero potential of buying post-Lease
Advanced
Joined: Feb 2005
Posts: 564
Likes: 162
From: Mid-West
So, a leasee thinking is: I will gun down this car here and there, use cheapest gas and, perhaps skip maintenance, as this is not my car and let’s the second owner deal with all the issues later. If any of above is true, nice attitude.
Last edited by Lex2000TL; Jun 4, 2023 at 04:35 PM.
What in your infinite wisdom makes you think 87 octane would risk damaging your engine?
Driver School Candidate
Joined: Aug 2022
Posts: 18
Likes: 18
From: NC
But some quick (credible?) searches show nearly 2/3 of new Lexus are leased, which surprised me greatly. And made me realize some with this view point on mpg savings may have different views
If I were to Lease I’d get something more fun/exciting and thus less reliable if I wasn’t going to drive it long term
Pole Position
Joined: Jun 2010
Posts: 3,169
Likes: 1,714
From: NC
Used 87 octane in last seven vehicles with over one million miles driven. Some recommended premium some required it. Never had one engine problem. Never noticed any difference in mpg or acceleration. There are so many sources stating this very thing. Just one is go to YouTube and search premium gas versus regular gas CBC.
