This hasn't been true for most toyotas I've own. It's true at least for the nissan and American brands that I've owned. Toyota tunes are too conservative and retard timing. This has been my experience with most toyotas I've own, from my old rav4 to my ISF. They all have benefited from running higher octane. This is also highly dependent on your location as well. I haven't tested the LX but plan to do so eventually.
Poll - LX570 owners using regular 87 octane or Premium
- Thread starter SWUtah
- Start date
This site may earn a commission from merchant affiliate
links, including eBay, Amazon, Skimlinks, and others.
This hasn't been true for most toyotas I've own. It's true at least for the nissan and American brands that I've owned. Toyota tunes are too conservative and retard timing. This has been my experience with most toyotas I've own, from my old rav4 to my ISF. They all have benefited from running higher octane. This is also highly dependent on your location as well. I haven't tested the LX but plan to do so eventually.
You should have run your ISF on 91 octane, that is what Lexus states in the manual. Running 87 and switching to 91 could have made a "notable" difference since the timing could have been retarded due to knock sensor readings BUT if the tune is designed for 87 it can't just "detect" the presence of a higher grade and increase timing over the standard tune so I believe that any difference noted (i.e. a RAV4) would be the placebo effect.
In older vehicles (read as carbureted or early injection) can use lower octane rated fuels at higher altitudes because the air is less dense, less air flows to your car's engine and translates to a slightly richer air-fuel ratio, and deters engine knock. but with modern ECU controlled engines the recommended octane rating should be used
I have seen someone posted the spark trim or maybe knock trim if there is such a thing. From what he posted, it does trims timing with regular vs premium (a long term trim) but I don't remember where that post is (one of those longer post than this one). It was like some graphic gauges and such
I do not know that data is part of ODB , extended protocol or how he obtained it.
I do not know that data is part of ODB , extended protocol or how he obtained it.
My ISF hasn't ran on anything but 93 and above. I also don't consider data log readings placebo effects.
I recently (a year ago) replaced the plugs, coils, O2/Fuel, and MAF. Before this it didn't matter if I ran 87 or 91, the rig basically drove the same. After this the rig MUCH prefers 91. I wish I could say I got way better MPG on 91, but it's about the same as the price difference, 6-10%.
Wow you data logged your RAV? OK whatever on the RAV I'll assume you meant the ISF so above you say only 93 or higher on the ISF but earlier ...
there you stated they "benefited" from higher octane. If you have never run less than 93 how can you state a "benefit" ... either you ran both lower and higher to "data log" a difference or you didn't.
I'm not going to have a keyboard war over this ... I posted an objective test that showed for a given engine no real benefit was provided simply by using higher octane. You say your experience is different ok, but that is pretty subjective without comparative data.
I use regular in my 100 but premium in my LX570. They both ask for premium.
Call me crazy….
Call me crazy….
interesting experiences by different people.
I track my odometer and number of miles driven between tank fills. I can notice the difference not just between 87 to 93 octane but also difference in performance and mileage between different types of gas station brands (shell vs costco gas) etc. I dont believe this is just placbo effect as i have noticed this over a long period of time and have also noticed that some costco gas gave me better mileage (some gas stations tend to be better). I noticed it on my motorcycles and cars.
(I also account for same pattern of driving on same roads and measured on same stip of highways on cruise control for 100 miles). FWIW.
I track my odometer and number of miles driven between tank fills. I can notice the difference not just between 87 to 93 octane but also difference in performance and mileage between different types of gas station brands (shell vs costco gas) etc. I dont believe this is just placbo effect as i have noticed this over a long period of time and have also noticed that some costco gas gave me better mileage (some gas stations tend to be better). I noticed it on my motorcycles and cars.
(I also account for same pattern of driving on same roads and measured on same stip of highways on cruise control for 100 miles). FWIW.
My motorcycle experience was with ducati multistrada 2008 which takes premium fuel. and I am talking about the idle engine rev. It was different not just for premium vs regular fuel (Which is understandable as it requires premium) but also different idle engine between different types of gas stations.
Had a similar experience with yamaha vstar cruiser.
Gas at different gas stations in an area or city comes from the same source. I worked at oil refinery and every gas station in 100 mile radius had gas from our refinery which is the exact same gas. Now where the difference comes from is that each BRAND had their own proprietary formula which was pumped in each truck load whenever they pick a truck. the driver for shell will punch in their code and a small shot of maybe abt 1Liter would be pumped into their truck from their proprietary tank and then the gas will be filled into the tanker which will be delivered at shell station. Same for other brands like Valero or Love`s or any other brand picking up gas.
I can tell you that the gas of different octane levels are from same source which is very high octane levels and then at storage tanks they were blended in with heavy alkalyte which is very low octane to achieve target octane level. Also the 87 octane can be 88 or higher but not 86 in order to get certified. so the 87 octane gas will always be higher than 87.
i have owned 2008 lx570 from 2015 to 2020 and now 2016 lx570 since 2020 and has always put 87 grade in them. nothing but 87. Idont care about that 1 or 2 higher horse power.
My understanding is that newer car computers adjust to the detonation timing of different octanes which does not harm your engine but result in loss of 1 to 2 horsepower performance and i could be wrong.
I always fill with Shell brand since i know for a fact that their proprietary formula is far superior than other brands and keep the engine clean from gunk buildup.
I can tell you that the gas of different octane levels are from same source which is very high octane levels and then at storage tanks they were blended in with heavy alkalyte which is very low octane to achieve target octane level. Also the 87 octane can be 88 or higher but not 86 in order to get certified. so the 87 octane gas will always be higher than 87.
i have owned 2008 lx570 from 2015 to 2020 and now 2016 lx570 since 2020 and has always put 87 grade in them. nothing but 87. Idont care about that 1 or 2 higher horse power.
My understanding is that newer car computers adjust to the detonation timing of different octanes which does not harm your engine but result in loss of 1 to 2 horsepower performance and i could be wrong.
I always fill with Shell brand since i know for a fact that their proprietary formula is far superior than other brands and keep the engine clean from gunk buildup.
Sinister
SILVER Star
Nah you’re not crazy. For my 200 I was using 89 since day one. For the new LX 600 I just filled up for the first time and used 91. I figured that’s what they require and I’m not gunna use 89 (I would in a pinch though) so I’ll stick with the recommendation, not gunna sweat the yearly savings between 89 and 91+. So we may both be crazy?
It frustrates me to watch octane being characterized and simplified in such layman terms on a forum. With conclusions drawn from nothing more than a single anecdote. There's whole books with millions of R&D in real development. Octane is not just a notional 4 point difference from 87 to 91. Saying this as a previous tuner and engineering associated with platforms tuning for power and developing new motors.
Those that say it's a low compression V8, or compare to a old school v8 architecture, or that it is the same as the Tundra motor... The 3UR-FE may not be forced induction but it has mechanisms to change volumetric efficiency, aka dynamic compression, of the motor. This gives software the ability to be tuned to control, leverage, and and respond to octane or lack there-of. It is clear from the manufacture in documentation, the LX is tuned for and requires 91. The LC is tuned for 87, but may be able to benefit from higher octane.
I'll leave it at your car knows, and the only way it knows is because it is responding to low grade knock. There is not a direct sensor for octane. There are parameters like KCLV that can be read to confirm if the engine is responding to knock. Engine tuning is also a game of margin. Sure 87 may work commuting to work. But get a bad batch of 87 (whereas a bad batch of 91 will still be nominally closer to 91), on a really hot day, on vacation with a significant load, and grade. Maybe with a lifetime of low grade knock, microscopic pitting, and carbon because of uneven flame fronts... Maybe the motor won't ever grenade, but lost compression and leaking head gaskets aren't a great thing either.
Those that say it's a low compression V8, or compare to a old school v8 architecture, or that it is the same as the Tundra motor... The 3UR-FE may not be forced induction but it has mechanisms to change volumetric efficiency, aka dynamic compression, of the motor. This gives software the ability to be tuned to control, leverage, and and respond to octane or lack there-of. It is clear from the manufacture in documentation, the LX is tuned for and requires 91. The LC is tuned for 87, but may be able to benefit from higher octane.
I'll leave it at your car knows, and the only way it knows is because it is responding to low grade knock. There is not a direct sensor for octane. There are parameters like KCLV that can be read to confirm if the engine is responding to knock. Engine tuning is also a game of margin. Sure 87 may work commuting to work. But get a bad batch of 87 (whereas a bad batch of 91 will still be nominally closer to 91), on a really hot day, on vacation with a significant load, and grade. Maybe with a lifetime of low grade knock, microscopic pitting, and carbon because of uneven flame fronts... Maybe the motor won't ever grenade, but lost compression and leaking head gaskets aren't a great thing either.
While I don't disagree overall with what you are saying I do believe it should be simplified for a "drivers" forum where the discussion is need or isn't needed/use or don't use discussion. So in that regard it really is just the difference in the numbers because the tune is "fixed" we aren't making changes. Diving too deep is just as bad as the anecdotes from daily use.
The discussion moved from the initial question/survey of use to whether regular and premium differ and to whether it actually improve performance even when not required. The factory says 91 for LX and I agree with your last paragraph in that regard. An LC only requires 87 and I question whether any benefits can be had by adding octane. While it was a basic EFI V8, the Engine Masters test demonstrates that adding octane to a basic tune does nothing.
I do run 87 in my 200 which requires I get "midgrade" at my attitude since "regular" is 85 but last week Sam's Club was $2.69 for 85 so I did a "test". I knew I was making a road trip with two mattresses on the roof rack. On level ground using a light foot I got a "normal" (for me) 19 mpg but when I hit the hills and needed more throttle it was worse than pulling my trailer over the same route ... interesting but too subjective to be of any use. Meaning was poor mileage due to extra throttle needed due to low power because timing retardation or worse wind resistance than the trailer or ??? ... just a silly anecdote.
Another anecdote ... my 02 Tacoma was labeled for 87 Living in Den I used 85 and hot days on a grade it would ping like crazy, moved to Atl and ran 87 it was quiet as a mouse, moved back to Den and started 87 no ping ... sold it and got the 200 (if I'm paying for mid-grade I want mo powa
)Like you I have a Porsche and I have a Cobb tuner and I leave the mapping to the experts based on my mods and because 91 is the best I can do without a major trek. I make sure my tuner knows I want a map that is suited for that octane.
My "tuning" experience pre-dates ECUs and EFI, I learned to prevent detonation by managing compression, timing mixture ect. during the build/tuning, there was nothing rolling back my timing on the fly ... s*** worked or blew up.
A minor quibble with your wording here. Respond to lack of octane (as evidenced by knocking)? Sure, if the engine knocks it can retard the timing to reduce or eliminate knocking. But no, the software can't "control" (i.e., change) octane.
Yessir, agreed. I was trying to say that the ECU has control to manage octane requirements of the motor. Timing advance is one way. It can also control volumetric efficiency with cam phasing (VVTi). This determines how deep the engine breaths / dynamic compression / octane requirements.
I'm not sure whether you're aware but there are higher octanes than 93. So to explain it clearer with my two examples, the rav4 required 87, it benefited from running higher octane. My ISF requires 93, it benefited from running higher octane. Yes, I try to data log all my cars. It's a simple and straight forward process and a good way to see the general health of your engines. To see how fuel affects your car, you don't even need to data log, just monitor a few parameters.
LOL yeah I am aware and as I stated in another post I have used 106 (in the early 70s we could still get leaded 100 at the pumps)
Clearly you are not aware of the ISF requirements ... from the manual:
so 91 is the listed octane for the US, in case you didn't know the US doesn't use RON (research octane rating) as the benchmark, the US uses MOR (motor octane rating) and 91 is the minimum to be considered premium even if you see 93 at the pump.
My mistake. It does require 91. I usually fill with 93 because that's what's mostly available in my area. It still benefits from higher octane which is what we've been discussing.
The answer is an absolute yes, and you experienced it here firsthand. I would bet if you monitored the KCLV parameter (knock correction learning value), it would confirm your impressions. I can see when towing, with the higher (heat) demand on the engine, it'll show an incrementally lower value (less timing). The difference here is that the ECU is gently optimizing vs riding the knock threshold.
The Engine Masters test while interesting, is not representative. (I enjoy the series also btw!) A quick pull on an engine stand of an old school LS pushrod architecture isn't the same as a modern DOHC VVTi engine in chassis, perhaps heat soaked, accelerating or climbing grade. It's this use case - sustained high engine output that would result in high thermal loads and combustion pressures - where insufficient octane will show it's limitations. Without enough octane, the engine will experience pre-ignition and knock, and it'll have to back off timing. Maybe worth repeating again, there is real knock going on as it's the only way the ECU gets feedback to know to back off.
Backing off timing is not a magic solution either, because while it solves one problem, it can create others like lost performance, poor gas mileage, and other downstream issues. Backing off timing severely reduces adiabatic efficiency (energy extracted from combustion). That excess thermal energy gets pushed into the exhaust leaving the catalytic converters to do more work. Over the lifetime of the vehicle, and the cats are sure to wear out faster, and that's not a cheap component.
Last edited:
I think we are in complete agreement about using the appropriate grade fuel, to summarize and address the OP... incorrect fuel grade and insufficient octane rating can reduce performance and potentially subject the engine to damage.
In later posts it seemed that others were advocating the use of higher grade/octane fuel to increase performance/mileage on engines designed to operate on lower grade fuels .... that was the intent of the Engine Master posts to show that in a specific objective test (anecdotes are subjective tests) no improvement was noted. I believe that in my 200 I would get no advantage to running premium all the time. That being said .... it is possible that in a situation like you describe that I could see LESS performance degradation by running 91 octane but not truly an increase hp and mileage. I guess it really is semantics but in summation the best I can achieve with 91 is just normal performance in a worse case situation ( and yes that is a good thing)
