Yikes!!!
03-10-23 | 06:40 AM
#31
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Joined: May 2012
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From: Maryland
Where in a Sienna's owners manual does it say Toyota reccomends premium fuel for ALL its vehicles? It says they reccomend Top Tier fuels, but not premium fuel. Top Tier is a detergent grade of gasoline...
03-11-23 | 01:34 PM
#33
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Joined: Sep 2014
Posts: 615
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From: IL
87 has plenty of detergent in it, if you buy a major brand. So no advantage there. Higher octane gas burns slower, so it resists detonation under high load. But the BTU content per gallon is the same. Knock is more likely at low RPM and high load, like in 8th gear when there's a mild uphill grade and no downshift occurs.
In any case, there are 4 knock sensors in the valley to pick up abnormal combustion. The ECM will retard timing temporarily if knock is detected. If you accelerate gently, there's probably not much difference in performance or fuel economy between regular and premium.
On a turbo DI engine, it might make more of a difference.
In any case, there are 4 knock sensors in the valley to pick up abnormal combustion. The ECM will retard timing temporarily if knock is detected. If you accelerate gently, there's probably not much difference in performance or fuel economy between regular and premium.
On a turbo DI engine, it might make more of a difference.
03-11-23 | 02:08 PM
#34
Lexus Champion
Joined: Oct 2019
Posts: 11,871
Likes: 1,264
From: Ohio
87 has plenty of detergent in it, if you buy a major brand. So no advantage there. Higher octane gas burns slower, so it resists detonation under high load. But the BTU content per gallon is the same. Knock is more likely at low RPM and high load, like in 8th gear when there's a mild uphill grade and no downshift occurs.
In any case, there are 4 knock sensors in the valley to pick up abnormal combustion. The ECM will retard timing temporarily if knock is detected. If you accelerate gently, there's probably not much difference in performance or fuel economy between regular and premium.
On a turbo DI engine, it might make more of a difference.
In any case, there are 4 knock sensors in the valley to pick up abnormal combustion. The ECM will retard timing temporarily if knock is detected. If you accelerate gently, there's probably not much difference in performance or fuel economy between regular and premium.
On a turbo DI engine, it might make more of a difference.
High octane doesn't burn slower, it has higher activation energy requirements
The resistance to detonation is solely the higher activation energy allowing a higher compression PSI before auto ignition due to the temp increase resultant of STP law.
The ECU will CONSTANTLY attempt to hit full spec spark and VVT timing advance and when, not if WHEN knock occurs with lower than spec fuel it will back off and then creep back toward target until it knocks again. It will be an endless loop that will pile on small damage constantly....unless you run fuel that allows the ECU to use the map it is programmed for.
Look up KLCV on this forum to understand more.
03-11-23 | 11:08 PM
#36
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Joined: Jan 2012
Posts: 147
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From: ohio
The argument hasn't been settled. One opinion is to use highest octane possible and get 40mpg and run a 12 sec quarter mile. Another opinion is low octane and cough and sputter and get 10mpg with 19 sec quarter miles. In reality, my experience is lose of maybe one to two miles per gal and a couple tenths in the quarter mile. Every twenty gals I keep an extra twenty dollars in my pocket.
Good or bad. Just ordered six bottles of Chevron Techron. That's a year supply for the SC, LS and RX. Got to keep the fuel system clean.
Good or bad. Just ordered six bottles of Chevron Techron. That's a year supply for the SC, LS and RX. Got to keep the fuel system clean.
03-12-23 | 07:09 AM
#37
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Joined: May 2012
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From: Maryland
If you use top tier gas additives like Techron are a total waste of money. Better to put that money towards running the proper fuel.
If Lexus thought fuel additives were worthwhile they would put them in the maintenance schedule.
If Lexus thought fuel additives were worthwhile they would put them in the maintenance schedule.
03-12-23 | 10:23 AM
#38
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Joined: Oct 2019
Posts: 11,871
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From: Ohio
The argument hasn't been settled. One opinion is to use highest octane possible and get 40mpg and run a 12 sec quarter mile. Another opinion is low octane and cough and sputter and get 10mpg with 19 sec quarter miles. In reality, my experience is lose of maybe one to two miles per gal and a couple tenths in the quarter mile. Every twenty gals I keep an extra twenty dollars in my pocket.
Good or bad. Just ordered six bottles of Chevron Techron. That's a year supply for the SC, LS and RX. Got to keep the fuel system clean.
Good or bad. Just ordered six bottles of Chevron Techron. That's a year supply for the SC, LS and RX. Got to keep the fuel system clean.
You might want to use straight 30 weight oil as well to save money lol!
03-12-23 | 04:38 PM
#39
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Joined: Jan 2012
Posts: 147
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From: ohio
No 30 weight for me. I use straight STP cut with Motor Honey. I can't hear any motor noise at all. I can't tell if I'm using oil, I can't pull the dip stick. It's like a sword stuck in a stone. Techron maybe a waist, 230k,170k and 150k on my three Lexus I have now and 150k on two previous lexus with no injector problems, tells me keep on using the Techron.
Think about this. Knock sensors retard timing when a knock is sensed. They obviously retard more on 87. Don't you think timing is also retarded on 91 or 93? To eliminate all knock what octane must we use? Is there a limit? Is 104 sufficient or should we go right to aviation gas, eliminate micro knocks?
Think about this. Knock sensors retard timing when a knock is sensed. They obviously retard more on 87. Don't you think timing is also retarded on 91 or 93? To eliminate all knock what octane must we use? Is there a limit? Is 104 sufficient or should we go right to aviation gas, eliminate micro knocks?
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Tec80 (03-12-23)
03-12-23 | 05:30 PM
#40
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Joined: May 2012
Posts: 58,118
Likes: 2,786
From: Maryland
No 30 weight for me. I use straight STP cut with Motor Honey. I can't hear any motor noise at all. I can't tell if I'm using oil, I can't pull the dip stick. It's like a sword stuck in a stone. Techron maybe a waist, 230k,170k and 150k on my three Lexus I have now and 150k on two previous lexus with no injector problems, tells me keep on using the Techron.
Think about this. Knock sensors retard timing when a knock is sensed. They obviously retard more on 87. Don't you think timing is also retarded on 91 or 93? To eliminate all knock what octane must we use? Is there a limit? Is 104 sufficient or should we go right to aviation gas, eliminate micro knocks?
The best way to maintain a car is to follow the factory guidelines at a minimum, use the specified fuel, specified fluids, specified intervals...the engineers that designed the vehicle specified all of that for a reason. My cars that specify 87 get 87, the ones that specif7 91 get 93 (we don't have 91 here). It calls for a specific weight oil? Thats what I use.
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Striker223 (03-13-23)
03-13-23 | 08:17 AM
#41
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Joined: Nov 2014
Posts: 659
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From: Georgia
No, because the ECM is designed for the car to run on 91 octane, the knock sensors don't retard timing because the timing is set for 91 octane, so there isn't any knock. Anything more than that provides no benefit. Its the same reason running premium in a vehicle designed for 87 provides no benefit.
The best way to maintain a car is to follow the factory guidelines at a minimum, use the specified fuel, specified fluids, specified intervals...the engineers that designed the vehicle specified all of that for a reason. My cars that specify 87 get 87, the ones that specif7 91 get 93 (we don't have 91 here). It calls for a specific weight oil? Thats what I use.
The best way to maintain a car is to follow the factory guidelines at a minimum, use the specified fuel, specified fluids, specified intervals...the engineers that designed the vehicle specified all of that for a reason. My cars that specify 87 get 87, the ones that specif7 91 get 93 (we don't have 91 here). It calls for a specific weight oil? Thats what I use.
I run the specified oil viscosity, and the specified oil change intervals. If any engineers know what they're doing, it is TOYOTA engineers. I run no additives in any fluid of any vehicle I have ever owned. Including my Cummins Ram. And they've never had a fuel or oil related issue (yet). 200k miles on the Cummins, runs loud a (loud-***) dream.
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SW17LS (03-13-23)
03-13-23 | 12:01 PM
#42
Lexus Champion
Joined: Oct 2019
Posts: 11,871
Likes: 1,264
From: Ohio
No 30 weight for me. I use straight STP cut with Motor Honey. I can't hear any motor noise at all. I can't tell if I'm using oil, I can't pull the dip stick. It's like a sword stuck in a stone. Techron maybe a waist, 230k,170k and 150k on my three Lexus I have now and 150k on two previous lexus with no injector problems, tells me keep on using the Techron.
Think about this. Knock sensors retard timing when a knock is sensed. They obviously retard more on 87. Don't you think timing is also retarded on 91 or 93? To eliminate all knock what octane must we use? Is there a limit? Is 104 sufficient or should we go right to aviation gas, eliminate micro knocks?
Think about this. Knock sensors retard timing when a knock is sensed. They obviously retard more on 87. Don't you think timing is also retarded on 91 or 93? To eliminate all knock what octane must we use? Is there a limit? Is 104 sufficient or should we go right to aviation gas, eliminate micro knocks?
STP cut with an additive.....yep that tracks lol!
03-16-23 | 10:28 AM
#43
Dysfunctional Veteran
Joined: Sep 2004
Posts: 7,828
Likes: 160
From: Van Alstyne, TX
Running regular in a Lexus designed for premium fuel is a great way to have to drop $4,000+ replacing catalytic converters. Don't do it. And no, you can't run aftermarket cats on these cars. For some reason, they only run correctly with CC's from Toyota/Lexus. I have played that game more than a few times on Lexus cars. Every time I replaced a cat with a non-OEM, it works for a few weeks and throws a CEL/runs like ***. Drop the coin for OEM cats, and it fixes it every time.
03-16-23 | 10:55 AM
#45
Dysfunctional Veteran
Joined: Sep 2004
Posts: 7,828
Likes: 160
From: Van Alstyne, TX
I was buying older/higher mileage Lexus cars, and they weren't always taken care of by previous owners. I have owned more Lexus/Toyota cars than most people have owned, just cars, in their lives. My current 2008 LS460 only has 120k on it, and I have had it since 83k, so I got ahold of it in time to keep it maintained properly.