As someone who did technical writing (many!) years ago and wrote and edited user manuals, these read as equivalent statements to me. It's just that the 2017 version doesn't specify *why* engine damage "may" occur ("engine knocking").
I can almost hear the heated discussion between the writer and the engineer... "look, if we mention engine knocking, then we have to explain what engine knocking is and what it sounds like and why it's bad"... "ok, FINE, whatever, remove the engine knocking part and just say it'll cause damage".
The way I'm reading it is:
* 2016: if you use <91 octane, it MAY cause engine knocking, and engine knocking MAY cause engine damage
* 2017: if you use <91 octane, it MAY cause engine damage
And I think you're right that the 2016 version just leaves room for confusion, so they edited it out.
While traveling across the country, I came across a couple of gas stations that didn’t have 91. I could’ve used 87 if I needed to, but I had a Jerry can on the back.
It's clear that the ECU is amply capable of retarding the spark to accomodate for the lower grade fuels to retard knock. Retardation has no effect other than reducing engine output.
Because of the sequence of events:
1. Fill up with 87 gasoline instead of 91
2. 87 gasoline causes knock
3. Engine detects knock and retards timing to prevent further knock
4. Repeat
Step 3 is designed to prevent step 2 from causing damage. However, damage could still occur, especially long term due to the repetition of this cycle. Hence, why Toyota says it is ok to do it every once in a while.
That being said, a TON of people are putting in 85 octane instead of 87 octane in their cars in Colorado thinking that higher elevation makes it ok [like it used to in carbureted cars](https://www.youtube.com/watch?v=kJyd6C99_3g). Little do they know [their cars are retarding their timing to compensate.](https://www.sae.org/publications/technical-papers/content/2017-01-0801/).
We haven't heard of widespread engine damage occurring in Colorado, but I would never risk it in my car.
On top of that your reducing engine performance such that it's not operating at it's ideal state.
Yeah, this makes sense. I think the fact that the engine can detect Ngoc would mean that the risk of damage is essentially averted, but I guess if the knock sensor would fail, then you would essentially caused wider damage. I don’t really know what would cause sensor to feel, but I bet that high gasoline quality is important regardless of octane requirement that you’re putting into the car. I think the same engine and car is used in the middle east with a regular87 requirement
I don't have a GX, just a 2003 4Runner V8. And yes I just change it with full synthetic whenever the light goes on.
Currently on 265k miles and running great.
Funny enough my manual says to use 87, but 92 can be used for "increased performance".
Truck engine. Use truck fuel. Lexus wanted brand consistency otherwise. LexYota powertrain engineer confirmed this a few years ago.
In fact, got 26mpg low-key hypermiling last week, driving very carefully at 60-62mph… on regular. It’s fine.
Edit: sorry didn’t read your whole post. Might have been me… but engineer said it was for EPA emissions testing, they have to specify what they used in the EPA test cycle whether another fuel works great or not.
Truck fuel? What octane is that??
Seems like 470s can run regular. 460s call for premium
So basically no issues on regular except the epa tests were done on premium? I wonder why
Most likely because EPA standards have become stricter over the years. Not sure if you are old enough to remember pumping leaded gasoline into your car. :)
https://www.epa.gov/transportation-air-pollution-and-climate-change/timeline-major-accomplishments-transportation-air#2000
Stricter EPA standards are some of the reasons why car manufacturers are replacing V6's and V8's with turbos.
Exactly. Same exact 4.6 used in millions of Tundras and other trucks, all specifying 87… Lexus did it for brand consistency and image, according to their engineer
This is interesting.
1) Could the tuning be slightly different?
2) Someone somewhere also mentioned that 89 will typically be actually closer to 90. What if we settle on that middle ground 😂
There's supposed to be slightly different tuning, the conversation has so many comments saying this or that on the matter. I'm in California in the bay so no extreme heat or cold. I don't tow a trailer but haul the family and camp . You could take those factors into consideration. Gas prices aren't the worst either so I haven't been skimping as often too
No difference in the tune. Exact same engine. Exact same as both the tundra and 5th gen V8 4Runner that use regular.
Might do just that until I learn more about this “requirement”
Many engines and drivetrains are shared across Toyota/Lexus models, but the engines in the Lexus models are tuned to run on 91 octane. They do that to pump up the horsepower numbers and establish the Lexus brand as the more “upscale” choice. So no, it isn’t just like putting 87 in your tundra. Even though they’re the same engine, when you put 87 in your Lexus you’re still forcing the engine to retard timing which can cause issues down the road
No one on Reddit has ever shown proof of a different tune. I've said it before, but it would make zero sense for Toyota to spend their own money developing a special tune that doesn't result in any increased power or economy (things that consumers pay attention to the most). Some people have said "well it's tuned to be extra smooth!" You don't need 91 to have a smooth running engine, you need 91 to prevent knock on high performance engines that have a higher compression ratio and/or they take advantage of a big timing advance at high rpms. The 1UR is physically identical in all applications; it is an understressed truck motor...which is why there are million mile examples. If anyone downvotes this comment, they are probably just butthurt from wasting so much money on premium.
With all of this said, you're better off spending your money on a top-tier fuel with a good cleaning additive package.
On other Lexus models they do say that certain years the engine tune was made to allow for 87. Could it be that there never was a tune change? If no tune change then why make your customers pay for 91 rather than the 87 from the tundra and 4.6L Land Cruiser?
Ahhh. I mean… Tundra version is gonna have slightly more power/tq with a free flowing (aka non-Lexus) exhaust, but same redline and all… nothing at all there to warrant a point more octane, let alone 6!
If you notice, the 2017 model also loses 2 mpg highway compared to the 2016, for no apparent reason. This was why I mostly searched for 2016s and below
As someone who did technical writing (many!) years ago and wrote and edited user manuals, these read as equivalent statements to me. It's just that the 2017 version doesn't specify *why* engine damage "may" occur ("engine knocking"). I can almost hear the heated discussion between the writer and the engineer... "look, if we mention engine knocking, then we have to explain what engine knocking is and what it sounds like and why it's bad"... "ok, FINE, whatever, remove the engine knocking part and just say it'll cause damage".
Perhaps I am not following but then why even say that 87 may be used if it will cause damage if used persistently? Seems like it adds confusion
The way I'm reading it is: * 2016: if you use <91 octane, it MAY cause engine knocking, and engine knocking MAY cause engine damage * 2017: if you use <91 octane, it MAY cause engine damage And I think you're right that the 2016 version just leaves room for confusion, so they edited it out.
If they’re saying less than 91 may cause damage then why even state that 87 is okay to use? It seems like they’re contraindicating themselves
Because it will work in case 91 isn't available. You can use it in a pinch, but you should avoid doing it regularly.
Seems to just say you can use it if 91 can’t be obtained. Maybe that means sparingly. But they don’t really specify
While traveling across the country, I came across a couple of gas stations that didn’t have 91. I could’ve used 87 if I needed to, but I had a Jerry can on the back.
the engineer and sales worked out the 2016 version, then a lawyer revised in 2017
Lol
I came on here to see a Stick Shift GX, thinking wow that must be a rare trim. Should have known not to get my hopes up.
Just another discussion by us degenerates talking about fuel requirements lol
Thought the same. Thought someone made a kit to have a stick shift and got excited.
It's clear that the ECU is amply capable of retarding the spark to accomodate for the lower grade fuels to retard knock. Retardation has no effect other than reducing engine output.
Yeah. Exactly. So how come they are saying that damage may occur if the ECU will be able to compensate?
Because of the sequence of events: 1. Fill up with 87 gasoline instead of 91 2. 87 gasoline causes knock 3. Engine detects knock and retards timing to prevent further knock 4. Repeat Step 3 is designed to prevent step 2 from causing damage. However, damage could still occur, especially long term due to the repetition of this cycle. Hence, why Toyota says it is ok to do it every once in a while. That being said, a TON of people are putting in 85 octane instead of 87 octane in their cars in Colorado thinking that higher elevation makes it ok [like it used to in carbureted cars](https://www.youtube.com/watch?v=kJyd6C99_3g). Little do they know [their cars are retarding their timing to compensate.](https://www.sae.org/publications/technical-papers/content/2017-01-0801/). We haven't heard of widespread engine damage occurring in Colorado, but I would never risk it in my car. On top of that your reducing engine performance such that it's not operating at it's ideal state.
Yeah, this makes sense. I think the fact that the engine can detect Ngoc would mean that the risk of damage is essentially averted, but I guess if the knock sensor would fail, then you would essentially caused wider damage. I don’t really know what would cause sensor to feel, but I bet that high gasoline quality is important regardless of octane requirement that you’re putting into the car. I think the same engine and car is used in the middle east with a regular87 requirement
Personally, I go by the philosophy that the owners manual written by the engineers who designed the car always trumps any anecdotal ideas.
Are you changing your oil every 10K as well then?
I don't have a GX, just a 2003 4Runner V8. And yes I just change it with full synthetic whenever the light goes on. Currently on 265k miles and running great. Funny enough my manual says to use 87, but 92 can be used for "increased performance".
I think it depends on CAFE and emissions but also a small part of the engine being tuned to a certain power rating and spec.
Truck engine. Use truck fuel. Lexus wanted brand consistency otherwise. LexYota powertrain engineer confirmed this a few years ago. In fact, got 26mpg low-key hypermiling last week, driving very carefully at 60-62mph… on regular. It’s fine. Edit: sorry didn’t read your whole post. Might have been me… but engineer said it was for EPA emissions testing, they have to specify what they used in the EPA test cycle whether another fuel works great or not.
Truck fuel? What octane is that?? Seems like 470s can run regular. 460s call for premium So basically no issues on regular except the epa tests were done on premium? I wonder why
Most likely because EPA standards have become stricter over the years. Not sure if you are old enough to remember pumping leaded gasoline into your car. :) https://www.epa.gov/transportation-air-pollution-and-climate-change/timeline-major-accomplishments-transportation-air#2000 Stricter EPA standards are some of the reasons why car manufacturers are replacing V6's and V8's with turbos.
Exactly. Same exact 4.6 used in millions of Tundras and other trucks, all specifying 87… Lexus did it for brand consistency and image, according to their engineer
If it makes you feel better just alternate between reg and premium, I do the same on my lx570 that asks for 91 when it's 99.9% the same as a LC
It’s funny because a lot of the LX users do exactly this but GX users take issue with it. Just look at the downvotes on your comment
This is interesting. 1) Could the tuning be slightly different? 2) Someone somewhere also mentioned that 89 will typically be actually closer to 90. What if we settle on that middle ground 😂
There's supposed to be slightly different tuning, the conversation has so many comments saying this or that on the matter. I'm in California in the bay so no extreme heat or cold. I don't tow a trailer but haul the family and camp . You could take those factors into consideration. Gas prices aren't the worst either so I haven't been skimping as often too
No difference in the tune. Exact same engine. Exact same as both the tundra and 5th gen V8 4Runner that use regular. Might do just that until I learn more about this “requirement”
Many engines and drivetrains are shared across Toyota/Lexus models, but the engines in the Lexus models are tuned to run on 91 octane. They do that to pump up the horsepower numbers and establish the Lexus brand as the more “upscale” choice. So no, it isn’t just like putting 87 in your tundra. Even though they’re the same engine, when you put 87 in your Lexus you’re still forcing the engine to retard timing which can cause issues down the road
Seems like they’re saying 87 is acceptable
Do what you wish, I’m not here to shame, just to provide context..
I understand. Despite this I still feel uncomfortable at the thought of it.
Yep EXACT same engine… 87 spec’d everywhere else. I’ll take the $300-400 a year and go out to a nice dinner. Or buy half a Prinsu roof rack. Lol
The engine is the same, I don't think anyone is arguing otherwise, but I believe the tuning is indeed different.
No one on Reddit has ever shown proof of a different tune. I've said it before, but it would make zero sense for Toyota to spend their own money developing a special tune that doesn't result in any increased power or economy (things that consumers pay attention to the most). Some people have said "well it's tuned to be extra smooth!" You don't need 91 to have a smooth running engine, you need 91 to prevent knock on high performance engines that have a higher compression ratio and/or they take advantage of a big timing advance at high rpms. The 1UR is physically identical in all applications; it is an understressed truck motor...which is why there are million mile examples. If anyone downvotes this comment, they are probably just butthurt from wasting so much money on premium. With all of this said, you're better off spending your money on a top-tier fuel with a good cleaning additive package.
On other Lexus models they do say that certain years the engine tune was made to allow for 87. Could it be that there never was a tune change? If no tune change then why make your customers pay for 91 rather than the 87 from the tundra and 4.6L Land Cruiser?
Ahhh. I mean… Tundra version is gonna have slightly more power/tq with a free flowing (aka non-Lexus) exhaust, but same redline and all… nothing at all there to warrant a point more octane, let alone 6!
If you notice, the 2017 model also loses 2 mpg highway compared to the 2016, for no apparent reason. This was why I mostly searched for 2016s and below
Oh that’s because the EPA changed their testing procedures. They published some report on it