gcskoor

Gosh, do I really want to jump into something that seems clear in an Lexus manual? LOL

See below AAA study on engines that "recommend" but "do not require" premium fuel, which is wording in the 350h fuel specifications. As some stated, manual is wrong or poorly written. If true, I hope they quickly update the manual for it clearly seems to make that distinction of gas grades that can be used safe and the trade-offs. In others words, if premium is required just say it.

I think the only issue is 87 safe to use and/or is any performance reductions important to you. It has nothing to do with how much the car cost or your gas budget- that might influence one, but it not the questions.

For myself, if I ever get a 350h, I will likely use premium, since the regular in Colorado is 85- clearly not within the engine specs. However, my older Camry has the V6 has the same fuel recommendation- recommend premium, but does not required. I have used 85 regular in it for years before I realized Colorado's reduced octane. But when it was new, I could tell no difference in performance with premium- as the AAA study indicates. in fact, if you tell anyone not to use regular Colorado gas in their gas- you get the deer-in-the-headlight look. You will see most, if not all, putting 85 in their cars putting for cars that say they need 87. The mid-grade is 87- most never use it. They just go regular or premium 91. And no one talks about their engine pinging.

YMMV and performance too.

BTW, if one starts to "read between the lines" in the owners manual on the NX 2022 0W-16 oil specification, it also say your may want to use a heavier weight old in some situations- and this wording is even more vague what situation applies to use 0W-20. Guess, I will stick to 0W-16 for now. Or maybe not in towing, high speeds and mountainous driving-then 0w-20? LOL

"An oil with a higher viscosity (one with a higher value) may be better suited if the vehicle is operated at high speeds, or under extreme load conditions" -- from Rav4H and similar for NX350h oil specs manuals."

703

Let me ask you a reverse question.

Why would Lexus specify premium fuel for many of their hybrids using the A25A-FXS engines? Including the ES300h and NX350h and NX450h? Toyota Crown in Japan with the same engine also requires premium. In fact all Japanese made Camry hybrids with that engine requires premium. The US market often have lower fuel requirements of the same vehicle than overseas models to address higher grades are not available at every petrol station.

Do you really think it’s just for fun and to hurt the customer in the pocket for zero gain in performance and emissions?

The engine in the NX has a different ECU tune to the RAV4.

Let me put this in another way, the US manual recommended premium, overseas manuals specify premium. You in this forum are recommending regular against Lexus spec.

Then the onus is on you to provide evidence that doing so will not reduce performance or the way the car drives.

midcow3

I think the quality control of gasoline outside the USA is not as stringent and the Lexus bean counters don't want lawsuits. The Lexus design engineers are using a high compression ratio to get the best mileage and best performance which requires more refines gas in third world countries. To be safe you make a general statement and Lexus lemmings follow Without questioning.

I actually am not recommending against Lexus specs. If you read it very carefully regular is acceptable ( legalize simplified) but the premium is recommended ( then no problems with countries with lower gasoline refinement standards or for the customer who doesn't understand what the pinging and knocking noise is, and ruins the engine because they were using marginal gasoline).

Interesting that you say the ECU is tuned differently on the RAV4. So what does that buy literally? So the RAV4 is detuned to use regular gasoline without ever knocking and yet gets better mpg and better acceleration. Maybe, But I am not buying it, but the NX is a heavyweight.

We apparently have different opinions and that is okay

YMMV,
MidCow3

P.S. - Japan has much more stringent engine longevity requirements than USA. Does premium gas requirements help meet those stringent requirements? Meh

P.S.S. - Many different cars, many self-tests of fuel grades, virtually no statistical difference; same findings as major car magazines. Kind of like masks being only 0.33% effective.

703

1. Countries like Australia and NZ are not third world countries with poor gas quality. They are highly regulated, the only difference are the proprietary fuel additives being used between say Mobil and BP.
2. A25A engine is more thermally efficient at higher RPM with Tier 2 (Premium) vs Tier 3 (Regular). This is a graph of the non-hybrid A25A. I expect the graph to be more pronounced with the Hybrid. Therefore, more horsepower with the same amount of fuel during higher torque applications. The NX350h is a heavy car compared to the RAV4, and the time the car spends in higher torque range would be more than the RAV4.

Freds430

If you want to buy premium buy it.

I currently have my seventh vehicle that required premium gasoline of which I have used regular. Tried many occassions on each with premium and noticed absolutely no difference. I remember a thread awhile back here on this issue and a member swore his vehicle drove better and even said the transmission shifted smoother. Each vehicle drove over 100,000 miles before trading in or selling. Had ZERO engine issues. Experimenting with the other two levels, I have noticed zero difference in gas mileage or performance. I have used 87 in cars that have required premium for over a million miles and have not had one problem.
I always revert back to two MIT graduates that are car mechanics who had a syndicated radio show called Car Talk for 35 years.
http://www.cartalk.com/content/premi...egular-0#myth4

From the USA Today:
The only modern engines that should really need premium are those with superchargers, which force-feed fuel into the cylinders. "You're driving along and just tramp the gas and the knock sensor cannot sense the knock fast enough in some cases," because the supercharger boosts pressure so fast, says Bob Furey, chemist and fuels specialist at General Motors.

Burning regular when the owner's manual specifies premium won't void the warranty, nor damage the engine, even the most finicky automakers say. "You're giving up perhaps just a little bit of performance that a customer wouldn't really even notice, it's so slight," says Furey.I have researshed on the net and can not find one article that confirms the need to use premium except in a high charged turbo engine.



Good article on gasoline grades.

https://www.consumerreports.org/car-...h-extra-price/

https://www.youtube.com/watch?v=FPPkPAbzwbU&t=403s&ab_channel=CBCNews

nitrolada

Looking at the numbers, can see there is a small difference in power curve, but so slight that majority will not notice it at all. I'm surprised difference is so small but I guess when you realize it's same engine as Toyota and power is so similar (without the bigger electric engine), can see why premium fuel is not required as per Lexus and only recommended
they didn't even bother to say how much difference in power between regular and premium like other makes where certain models can run on regular but premium recommended and different power numbers for each type
eg Mazda says 227 HP and 310 lb/ft torque on regular and 250hp and 320lb/ft on premium

thanks for posting and confirming, glad it's a hybrid and not FI, no need for premium, and seems difference so minor Lexus didn't even publish differences in power. I mean if it requires premium, then they'll say so just like for their other vehicles who requires it

midcow3

I see very little difference. We agree that the NX is a heavier car than the RAV. Higher torque is mainly for acceleration. The smarter Lexus drivers know how to hyper-drive

Peace, use regular, we differ in opinion

YMMV,

MidCow3

P.S, - I either go for high performance or high mileage cars, maybe it is just me trading Golf R manual for NX350h auto; I like the way my wife's 2020 Avalon Hybrid Limited drives ( similar to ES300h but without an awful touchpad)

Look

703

Its not the power curve you should be looking at. It’s the thermal efficiency. The difference is material. Again, not the same engine, the engine in the graph is recommended on regular.

703

Not offering an opinion. Lexus says premium is more optimal. independent testing shows premium is more thermally efficient. All other regions says premium is required.

All facts. Everything else I hear are just opinions.

nitrolada

fact is regular is all that is required in north america, all other regions are irrelevant. testing, other regions etc.. irrelevant..doubt any of us on here know better than toyota/lexus engineers, and if they say fuel required is 87, then that's what's required. not really mysterious when its in all the printed manuals

There's markets where they don't even have 87 octane, so makes sense toyota/lexus will have material relevant to specific markets...

all we have to go buy is clearly in manual and from toyota/lexus.... is that the car requires 87 octane and 91 is recommended. i'll trust toyota/lexus engineers over what people say on a forum

midcow3

I guess we should be retrofitting all electric engines or at least diesel. If we stick with gasoline the we need Mercedes AMG Formula 1 1.6L v6 turbocharged engine.

703

Fact #1 - I have never said the engine can't run on 87.
Fact #2 - Manual says 91 is optimal for performance. Testing conducted in the US by EPA also proves that. All relevant. Where you did read the testing is not conducted in the US? Provide evidence. I have thousands of data points on the test.
Fact #3 - You have contradicted yourself, if you trust Lexus engineers, then trust 91 is the most optimal for the engine in the NX. Not mysterious is it?
Fact #4 - I live in one of the other markets, and 97 octane / 91 RON is available at every petrol station.

BEARCATJER

For what it's worth...i have been driving a Lexus since 1996 and have never used anything but 87 octane gas in any model including LS, ES and RX models. I have never had an engine problem with any Lexus i owned and never noticed any semblance of poor engine performance. I am thinking about getting into an NX300 but if i cant use regular gas I will not do so. Maybe i have just been lucky?

midcow3

Let's see some performance comparison tests ...... because I am willing to be the actual performance gain is so minimal no one will even notice it.

Cheers, Let's go regular is will work and cost a lot less at the current inflationary gas prices.

YMMV,
MidCow3

midcow3

just an example of test data. Yes , AAA may not be the best motorhead source. But these are the kind of actual results you'll see:

https://newsroom.aaa.com/wp-content/...ORT-FINAL3.pdf

Guess what their conclusion was regarding emissions, performance, and mpg? Don't want to spoil your read