Premium Fuel or not?

[Esquire]

Toyota plays the Regular vs Premium trick with many of their vehicles.
For example, Toyota says that the 2.4L turbo (T24A) engine installed in a Toyota (Highlander, Grand Highlander) can use Regular gas. But the same engine in a Lexus (RX, NX) demands Premium.
Same with the non-turbo (A25A) engine - when installed in a RAV4 hybrid, Regular gas is OK, but if it is installed in a Lexus NX 350h, it's Premium "recommended".
The truth is that any of this engines can run on Regular gas, but it just won't perform the same. The anti-knock sensor will kick in and retard ignition to prevent the engine from damaging itself. Sometimes it's unnoticeable, sometimes it is. For example, many Highlander owners expressed drivability issue with Regular gas, that went away when they switched to Premium. Toyota eventually rolled out a TSB that supposedly corrects the problem by slightly adjusting the ECM software, but this didn't cure the problem completely.
Regular vs. Premium gas is not the only "trick" that Toyota plays with Toyota vs. Lexus brand vehicles equipped with exactly the same parts. For example, Toyota-branded vehicles don't have a recommended brake fluid replacement interval. The maintenance manual only says "check brake fluid condition, replace if necessary". But Lexus maintenance manual says "Replace every 30k or 40k miles" depending on model.
So why is Toyota doing this? It's targeting different consumers with different expectations. Toyota buyers are "budget conscious" so low cost of ownership / maintenance is an important factor. Most don't care if after 10 years the car doesn't perform as new, as long as it "runs good". Lexus owners expect "perfection" and reliability, and are willing to pay for it. They expect their 10 or 15 years old Lexus to look and drive just like new. Hence Lexus recommended maintenance schedule is more intense to ensure better long term performance.
Since LC is a fairly expensive vehicle and has always been associated with image of quality and reliability, Toyota fuel recommendation is based on the criteria of providing ultimate reliability and durability. A LC will run better and last longer on Premium gas, there is no question about it. Will the difference be 10% or 30% or 50% it's to be seen.
BTW - if you own a Toyota but want to maximize it's lifespan and reliability, follow the Lexus recommended maintenance schedule.

Yes. This.

Back in the '80s - '90s, German cars required 91 or 93 Octane. Not because it would perform better, run more smoothly, or accelerate more rapidly. It was required because if you didn't use high Octane, the cars would start very hard, run extremely ragged, knock upon acceleration, and foul out plugs faster than you could refill fuel.

Engineering has improved 1000 fold over the last 20 years. Not using a higher Octane will not destroy the engine as the engines are designed to tolerate lower Octanes. However, over time, using lower Octane will likely cause more unintended wear.

Go with the highest Octane possible. I put it in everything I own with an engine. They all perform better, operate more smoothly, and are more enjoyable to use. Even marine fuel, it is always a higher Octane. It is not referred to as Premium--it is just higher Octane. And as such, significantly higher priced.

My position stands with Premium.

 

[katekebo]

Just adding a little bit on the subject ...
As @Esquire mentioned, the issue with using low octane fuel in high compression engines is knocking (explosive pre-ignition). Knocking puts a lot of stress on rod and crankshaft bearings, and will lead to premature wear if not eliminated. Knocking typically occurs when the engine is at heavy load at low rpms.
Modern engines have knock sensors. These are basically accelerometers that detect the characteristic sharp "knock" on the cylinder head associated with explosive pre-ignition. Once knock is detected, the ECU will retard ignition and/or adjust air-to-fuel ratio to reduce / eliminate knocking. The key part here is "once knocking is detected". This means that knocking has to occur before the ECU can compensate for it. Without knocking, the knock sensor has nothing to detect to trigger a response.
While the time required to detect knock and correct for it is short, it does not eliminate knocking completely, it only reduces its duration.
While knock elimination system programmed in the ECU will prevent the engine from quick death due to prolonged, persistent knocking, even the short duration episodes will have an impact on engine longevity. Hence, using low octane fuel will always cause some premature wear / damage to the engine before the ECU has the chance to adapt. Knocking cannot be eliminate pre-emptively - it can only be corrected after it has initiated.

 

[TheBat]

I'm not sure that the knock sensor works the way it is being simplified here. It doesn't just back off timing to eliminate pre ignition, the ecu also advances timing and leans out the fuel mixture to increase both power and economy, until it senses that it went too far, so you can still get pre ignition even with better fuel. It is designed to sense it early enough to prevent damage.

 

[TakaraLC]

Just adding a little bit on the subject ...
As @Esquire mentioned, the issue with using low octane fuel in high compression engines is knocking (explosive pre-ignition). Knocking puts a lot of stress on rod and crankshaft bearings, and will lead to premature wear if not eliminated. Knocking typically occurs when the engine is at heavy load at low rpms.
Modern engines have knock sensors. These are basically accelerometers that detect the characteristic sharp "knock" on the cylinder head associated with explosive pre-ignition. Once knock is detected, the ECU will retard ignition and/or adjust air-to-fuel ratio to reduce / eliminate knocking. The key part here is "once knocking is detected". This means that knocking has to occur before the ECU can compensate for it. Without knocking, the knock sensor has nothing to detect to trigger a response.
While the time required to detect knock and correct for it is short, it does not eliminate knocking completely, it only reduces its duration.
While knock elimination system programmed in the ECU will prevent the engine from quick death due to prolonged, persistent knocking, even the short duration episodes will have an impact on engine longevity. Hence, using low octane fuel will always cause some premature wear / damage to the engine before the ECU has the chance to adapt. Knocking cannot be eliminate pre-emptively - it can only be corrected after it has initiated.

The ECU continuously adjusts parameters like iming, air-fuel mixture, etc based on real-time feedback from the engine. Over time, it optimizes these settings to match the fuel type and operating conditions, and these setting will be used for that tank of gas going forward. When a new tank of fuel is added, the ECU doesn't immediately know the exact characteristics of the fuel, but it begins to gradually readjust its parameters to optimize performance based on the new fuel. So initially there may be some knocking, but there is an eventual adjustment.

 

[cvx5832LC]

Will the difference be 10% or 30% or 50% it's to be seen.

In my case, over 34 tanks (17 each on regular and premium), the difference was 19.78 on Premium and 19.46 on Regular, a whopping 1.7% difference. That difference is so small I can attribute it to the 50deg mornings when I did the Regular portion of my test. Or even the traffic associated with the holidays. Whatever the cause for that small difference, it's negligible enough for me to continue using Regular.

 

[katekebo]

In my case, over 34 tanks (17 each on regular and premium), the difference was 19.78 on Premium and 19.46 on Regular, a whopping 1.7% difference. That difference is so small I can attribute it to the 50deg mornings when I did the Regular portion of my test. Or even the traffic associated with the holidays. Whatever the cause for that small difference, it's negligible enough for me to continue using Regular.

Premium vs Regular won't make any difference in mileage, but it will make a difference in engines longevity.
Premium gas has more detergent additives. It keeps injectors cleaner. Direct injection injectors have very small holes and keeping them clean is important. Now, you can pour a bottle of gasoline detergent additive in every tank to achieve the same effect ...
In low compression naturally aspirated engines, using Premium is a waste of money. But in high(er) compression, boosted, tight tolerance engines, higher octane means less knock, and generally better performance, especially under heavier load.
How much longer engine life you can get from this engine with Premium vs. Regular is hard to predict. Will the injectors last 60k miles or 100k miles with Regular gas vs. 200k miles with Premium ... only time will tell. Will the rod and main bearings last 10% or 50% longer ... is to be seen. But there are good reasons why Toyota recommends Premium. Honestly, spending $60k or more on a car just to skimp on fuel, oil changes or general maintenance sounds like bad economy.

 

[EOD Guy]

Pretty sure the difference in detergent levels between 87 and 91, same manufacturer, is insignificant. The difference is the octane level.

 

[katekebo]

One additional comment. When a manufacturer specifies fuel octane rating, oil quality or maintenance intervals, these are MINIMUM requirements.
Puting Regular gas when the manufacturer specifies Premium is like saying: "Toyota recommends oil change every 10k miles, but if I change it every 15k it will probably be OK." Yes, it will be OK - for a while. In the end, it's your car and your money ...

 

[LandcruiserNut]

Same ole, Same ole, sell it!!!! Save $$. Surely these are better discussion points for this forum.

 

[Esquire]

Same ole, Same ole, sell it!!!! Save $$. Surely these are better discussion points for this forum.

Amen.
If you’re worried about 91 Octane or getting outstanding fuel mileage with a Land Cruiser, buy something else.

Now let’s focus the more pressing matter: are our Land Cruisers melting in the sun?

 

[treadmark]

A lot of people refer to this as the same engine across vehicles. The tuning of the same basic engine across a given or multiple platforms can vary significantly, with some applications requiring regular or premium. It’s simple for me. Toyota requires premium as a minimum, so that’s what I’ll put in mine.

 

[ultane]

93 octane, ethanol free, for Miss Daisy..

 

[HarvLC]

All I know is that my monthly gas bill has decreased since selling the ‘02 LC and buying the ‘24 LC. The added cost of premium gas hasn’t offset the large efficiency gain over the old rig.

 

[TakaraLC]

Premium vs Regular won't make any difference in mileage, but it will make a difference in engines longevity.
Premium gas has more detergent additives. It keeps injectors cleaner. Direct injection injectors have very small holes and keeping them clean is important. Now, you can pour a bottle of gasoline detergent additive in every tank to achieve the same effect ...
In low compression naturally aspirated engines, using Premium is a waste of money. But in high(er) compression, boosted, tight tolerance engines, higher octane means less knock, and generally better performance, especially under heavier load.
How much longer engine life you can get from this engine with Premium vs. Regular is hard to predict. Will the injectors last 60k miles or 100k miles with Regular gas vs. 200k miles with Premium ... only time will tell. Will the rod and main bearings last 10% or 50% longer ... is to be seen. But there are good reasons why Toyota recommends Premium. Honestly, spending $60k or more on a car just to skimp on fuel, oil changes or general maintenance sounds like bad economy.

Premium and Regular fuel have more or less the same detergent level. But a higher compression engine will get better milage with higher octane fuel since it would achieve higher thermal efficiency when operation at higher compression ratios.

 

[Go4it]

Here is why I’m using regular fuel in my 2024 LC:

• The Cost
  Premium fuel is $1 more per gallon where I live. Over a year, that’s about $1,000 extra, and over 10 years, it’s $10,000. That’s a lot of money for a marginal performance gain. I’d rather put that money toward extra maintenance, like more frequent oil changes, which have a bigger impact on longevity.
• The Battery Will Go Before the Engine Does
  Let’s be honest—this is a hybrid. The battery is likely to need attention before the engine shows any wear. Whether you use regular or premium fuel, the engine will outlast the battery.
• The Same Engine Runs Regular Fuel in the Tacoma Hybrid
  The Land Cruiser shares its 2.4L turbo hybrid engine with the Toyota Tacoma Hybrid. Both engines have identical hardware, including the compression ratio and internal components. Toyota allows regular fuel for the Tacoma Hybrid, meaning the engine is engineered to safely handle lower-octane fuel without damage. Toyota would not design or market the Tacoma Hybrid to use regular fuel if it posed any risk of engine damage. The Land Cruiser’s premium recommendation seems more about optimizing performance and refinement rather than ensuring basic reliability.
• No Warning of Engine Damage in the Manual
  The Land Cruiser’s manual recommends premium fuel but doesn’t warn of damage if you use regular. Compare that to the Lexus GX550 manual, which explicitly says, “damage may occur” if you use less than 91 octane. The lack of this warning for the Land Cruiser tells me that regular fuel won’t harm the engine—it’s just about optimizing performance.
  
  
  
• Oil Maintenance Matters More Than Fuel
  Engine longevity is influenced far more by oil quality and change intervals than the octane rating of the fuel. Contaminated or degraded oil accelerates engine wear by affecting lubrication and causing internal damage.
  Using the money saved from avoiding premium fuel, I plan to change the oil every 5,000 miles or sooner.
• Why Does Toyota Recommend Premium? (just my speculation based on available information)
  EPA Regulations: Automakers face fines if their vehicles don’t meet fuel economy targets. Even with regular fuel, the Tacoma Hybrid achieves 24 MPG combined, but the Land Cruiser may fall just 0.2 MPG short of hitting 23MPG EPA threshold on regular fuel. By recommending premium fuel, Toyota ensures the Land Cruiser hits its MPG target, avoiding fines for every unit sold.
  Luxury Feel: Premium fuel reduces engine noise, vibration, and harshness (NVH). This aligns with the Land Cruiser’s image as a high-end, smooth-driving vehicle. I’ve noticed about a 10% increase in NVH with regular fuel, but the difference is subtle and not worth the significant cost of premium.

This is why I’m using regular fuel in my LC and not worried about It. (for now)

 

[EOD Guy]

But there's a sticker!

 

[TakaraLC]

Here is why I’m using regular fuel in my 2024 LC:

• The Cost
  Premium fuel is $1 more per gallon where I live. Over a year, that’s about $1,000 extra, and over 10 years, it’s $10,000. That’s a lot of money for a marginal performance gain. I’d rather put that money toward extra maintenance, like more frequent oil changes, which have a bigger impact on longevity.
• The Battery Will Go Before the Engine Does
  Let’s be honest—this is a hybrid. The battery is likely to need attention before the engine shows any wear. Whether you use regular or premium fuel, the engine will outlast the battery.
• The Same Engine Runs Regular Fuel in the Tacoma Hybrid
  The Land Cruiser shares its 2.4L turbo hybrid engine with the Toyota Tacoma Hybrid. Both engines have identical hardware, including the compression ratio and internal components. Toyota allows regular fuel for the Tacoma Hybrid, meaning the engine is engineered to safely handle lower-octane fuel without damage. Toyota would not design or market the Tacoma Hybrid to use regular fuel if it posed any risk of engine damage. The Land Cruiser’s premium recommendation seems more about optimizing performance and refinement rather than ensuring basic reliability.
• No Warning of Engine Damage in the Manual
  The Land Cruiser’s manual recommends premium fuel but doesn’t warn of damage if you use regular. Compare that to the Lexus GX550 manual, which explicitly says, “damage may occur” if you use less than 91 octane. The lack of this warning for the Land Cruiser tells me that regular fuel won’t harm the engine—it’s just about optimizing performance.View attachment 24056
  
• Oil Maintenance Matters More Than Fuel
  Engine longevity is influenced far more by oil quality and change intervals than the octane rating of the fuel. Contaminated or degraded oil accelerates engine wear by affecting lubrication and causing internal damage.
  Using the money saved from avoiding premium fuel, I plan to change the oil every 5,000 miles or sooner.
• Why Does Toyota Recommend Premium? (just my speculation based on available information)
  EPA Regulations: Automakers face fines if their vehicles don’t meet fuel economy targets. Even with regular fuel, the Tacoma Hybrid achieves 24 MPG combined, but the Land Cruiser may fall just 0.2 MPG short of hitting 23MPG EPA threshold on regular fuel. By recommending premium fuel, Toyota ensures the Land Cruiser hits its MPG target, avoiding fines for every unit sold.
  Luxury Feel: Premium fuel reduces engine noise, vibration, and harshness (NVH). This aligns with the Land Cruiser’s image as a high-end, smooth-driving vehicle. I’ve noticed about a 10% increase in NVH with regular fuel, but the difference is subtle and not worth the significant cost of premium.

This is why I’m using regular fuel in my LC and not worried about It. (for now)

The same warning is also on the LC manual, it is on the next page.

About the engine outlasting the battery, I think that is only partially true. The battery has 10 year 150,000 mile warranty, engine has 5 year 60,000 mile warranty, so it clear that Toyota's risk assessment puts more risk on engine failing than the battery failing. Plus, once a battery fails, it costs ~$3000 to buy a brand new battery, and ~$1500 to buy a refurbished battery. These are with todays prices, in 10 years batteries of this capacity will probably cost a lot less, since brand new 1st gen Prius batteries went from being $5000-6000 to replace to $1000-1500 today. If the engine fails, I brand new engine will cost ~$10,000 and a refurbished/scrap yard engine will cost ~$5,000 or so. Engine prices will probably not go down in 10 years.

 

[Area 51]

Lets see:
60-80K $ USD or your local equivalent for a new high tech Cruiser.
Premium or cheaper fluids and fuel?????
.Amazes me how long this has gone on.

 

[Hiker42]

Here is why I’m using regular fuel in my 2024 LC:

• The Cost
  Premium fuel is $1 more per gallon where I live. Over a year, that’s about $1,000 extra, and over 10 years, it’s $10,000. That’s a lot of money for a marginal performance gain. I’d rather put that money toward extra maintenance, like more frequent oil changes, which have a bigger impact on longevity.
• The Battery Will Go Before the Engine Does
  Let’s be honest—this is a hybrid. The battery is likely to need attention before the engine shows any wear. Whether you use regular or premium fuel, the engine will outlast the battery.
• The Same Engine Runs Regular Fuel in the Tacoma Hybrid
  The Land Cruiser shares its 2.4L turbo hybrid engine with the Toyota Tacoma Hybrid. Both engines have identical hardware, including the compression ratio and internal components. Toyota allows regular fuel for the Tacoma Hybrid, meaning the engine is engineered to safely handle lower-octane fuel without damage. Toyota would not design or market the Tacoma Hybrid to use regular fuel if it posed any risk of engine damage. The Land Cruiser’s premium recommendation seems more about optimizing performance and refinement rather than ensuring basic reliability.
• No Warning of Engine Damage in the Manual
  The Land Cruiser’s manual recommends premium fuel but doesn’t warn of damage if you use regular. Compare that to the Lexus GX550 manual, which explicitly says, “damage may occur” if you use less than 91 octane. The lack of this warning for the Land Cruiser tells me that regular fuel won’t harm the engine—it’s just about optimizing performance.View attachment 24056
  
• Oil Maintenance Matters More Than Fuel
  Engine longevity is influenced far more by oil quality and change intervals than the octane rating of the fuel. Contaminated or degraded oil accelerates engine wear by affecting lubrication and causing internal damage.
  Using the money saved from avoiding premium fuel, I plan to change the oil every 5,000 miles or sooner.
• Why Does Toyota Recommend Premium? (just my speculation based on available information)
  EPA Regulations: Automakers face fines if their vehicles don’t meet fuel economy targets. Even with regular fuel, the Tacoma Hybrid achieves 24 MPG combined, but the Land Cruiser may fall just 0.2 MPG short of hitting 23MPG EPA threshold on regular fuel. By recommending premium fuel, Toyota ensures the Land Cruiser hits its MPG target, avoiding fines for every unit sold.
  Luxury Feel: Premium fuel reduces engine noise, vibration, and harshness (NVH). This aligns with the Land Cruiser’s image as a high-end, smooth-driving vehicle. I’ve noticed about a 10% increase in NVH with regular fuel, but the difference is subtle and not worth the significant cost of premium.

This is why I’m using regular fuel in my LC and not worried about It. (for now)

I bet you're right about this being EPA driven.

 

[TakaraLC]

I bet you're right about this being EPA driven.

To be honest, I don’t buy that explanation. The use of premium vs. regular fuel makes no noticeable difference in MPG or emissions under EPA test conditions. While high-compression engines are more efficient with higher-octane fuel, the benefits only become apparent under high-load or high-performance conditions, such as wide-open throttle or near peak RPM or when the engine is very hot.

The EPA tests don’t evaluate MPG or emissions at 6,000 RPM or during scenarios like drag racing, so any potential gains from premium fuel wouldn’t be captured in their tests.

Plus, if it made any significant difference, Toyota would have said regular OK, premium recommended for Tacoma (like how Ford does), and would have published MPG values with premium fuel.

Perhaps they recommend premium for LC because the differences in engine cooling. If knocking that happens relatively early in the compression cycle, it cannot be prevented by retarding the ignition timing (as by definition it is happening before the ignition and cannot be prevented by delaying ignition). This can happen if the engine is hot and is under load (hence why manufacturers like ford recommend premium when towing). ECU can still prevent knocking by opening exhaust valves during compression to decrease piston pressure, but this is typically a last-resort measure since you are venting unburned fuel to exhaust, which shortens catalyst life.