Why Premium fuel for 350h?
11-26-23 | 11:02 AM
#1
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From: WA
Why Premium fuel for 350h?
This topic has had lots of treatments. A sizable number of owners use regular gas arguing it's the same motor, etc. as the RAV4 that calls for regular. So why does Lexus prefer premium in the 350h? Is there something about the Lexus that is some kind of tweak from the RAV4? Or some other explanation? I don't mind using premium as recommended--that's what I use. But what's the explanation for it? Thanks team.
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11-26-23, 01:28 PM
Racer
Joined: Dec 2012
Posts: 1,705
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From: Toronto, ON
The "atkinson" cycle engine used in the hybrid is very high static compression ratio engine. To get the max power out of a typical high compression engines often requires premium fuel to prevent damage from uneven fuel burning due to knocking (aka denotation, pre-ignition, etc). However the whole premise behind atkinson cycle engines is to limit air intake into the cylinder (sort of like an anti-turbo). Less air charge, less fuel, some less power but more room for complete combustion, so much more efficient and less emissions, hence being favoured in hybrid vehicles where electric drive can assist power. This reduced air charge actually reduces the actual compression ratio in most situations other than under full throttle. In normal everyday conditions regular will do perfectly fine and get you most miles for the buck. If you have your foot to the floor occasionally, regular will still be fine as the engine computer will limit knock by backing off power a tad. If however you have your foot to the floor often, premium will let the engine eek out extra power without the computer imposing its limits when using regular fuel to prevent knock.
PS it is not the same motor as the gas RAV4 or NX250. Same family though, but cylinder head is different. Also, Toyota tends to tune down compared with Lexus. Take for example the NX350 engine, T24A turbo requires premium in NX while the same engine in the Highlander does not, because the Toyota version is tuned down to make less power.
PS it is not the same motor as the gas RAV4 or NX250. Same family though, but cylinder head is different. Also, Toyota tends to tune down compared with Lexus. Take for example the NX350 engine, T24A turbo requires premium in NX while the same engine in the Highlander does not, because the Toyota version is tuned down to make less power.
11-26-23 | 11:51 AM
#2
Racer
Joined: Aug 2011
Posts: 1,617
Likes: 668
Use Regular
Use regular, save money. Here was a previous ad infinitium discussion if you like reading a lot 
: https://www.clublexus.com/forums/sho...errerid=161523 https://www.clublexus.com/forums/sho...errerid=161523
: https://www.clublexus.com/forums/sho...errerid=161523 https://www.clublexus.com/forums/sho...errerid=161523
11-26-23 | 01:28 PM
#3
Racer
Joined: Dec 2012
Posts: 1,705
Likes: 616
From: Toronto, ON
The "atkinson" cycle engine used in the hybrid is very high static compression ratio engine. To get the max power out of a typical high compression engines often requires premium fuel to prevent damage from uneven fuel burning due to knocking (aka denotation, pre-ignition, etc). However the whole premise behind atkinson cycle engines is to limit air intake into the cylinder (sort of like an anti-turbo). Less air charge, less fuel, some less power but more room for complete combustion, so much more efficient and less emissions, hence being favoured in hybrid vehicles where electric drive can assist power. This reduced air charge actually reduces the actual compression ratio in most situations other than under full throttle. In normal everyday conditions regular will do perfectly fine and get you most miles for the buck. If you have your foot to the floor occasionally, regular will still be fine as the engine computer will limit knock by backing off power a tad. If however you have your foot to the floor often, premium will let the engine eek out extra power without the computer imposing its limits when using regular fuel to prevent knock.
PS it is not the same motor as the gas RAV4 or NX250. Same family though, but cylinder head is different. Also, Toyota tends to tune down compared with Lexus. Take for example the NX350 engine, T24A turbo requires premium in NX while the same engine in the Highlander does not, because the Toyota version is tuned down to make less power.
PS it is not the same motor as the gas RAV4 or NX250. Same family though, but cylinder head is different. Also, Toyota tends to tune down compared with Lexus. Take for example the NX350 engine, T24A turbo requires premium in NX while the same engine in the Highlander does not, because the Toyota version is tuned down to make less power.
Last edited by Droid13; 11-26-23 at 01:32 PM.
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11-26-23 | 01:57 PM
#4
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From: WA
The "atkinson" cycle engine used in the hybrid is very high static compression ratio engine. To get the max power out of a typical high compression engines often requires premium fuel to prevent damage from uneven fuel burning due to knocking (aka denotation, pre-ignition, etc). However the whole premise behind atkinson cycle engines is to limit air intake into the cylinder (sort of like an anti-turbo). Less air charge, less fuel, some less power but more room for complete combustion, so much more efficient and less emissions, hence being favoured in hybrid vehicles where electric drive can assist power. This reduced air charge actually reduces the actual compression ratio in most situations other than under full throttle. In normal everyday conditions regular will do perfectly fine and get you most miles for the buck. If you have your foot to the floor occasionally, regular will still be fine as the engine computer will limit knock by backing off power a tad. If however you have your foot to the floor often, premium will let the engine eek out extra power without the computer imposing its limits when using regular fuel to prevent knock.
PS it is not the same motor as the gas RAV4 or NX250. Same family though, but cylinder head is different. Also, Toyota tends to tune down compared with Lexus. Take for example the NX350 engine, T24A turbo requires premium in NX while the same engine in the Highlander does not, because the Toyota version is tuned down to make less power.
PS it is not the same motor as the gas RAV4 or NX250. Same family though, but cylinder head is different. Also, Toyota tends to tune down compared with Lexus. Take for example the NX350 engine, T24A turbo requires premium in NX while the same engine in the Highlander does not, because the Toyota version is tuned down to make less power.
11-26-23 | 02:09 PM
#5
Pit Crew
Joined: Oct 2022
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From: CA
Do the math
I have seen this question posed on forums for the various cars I have owned in the past including even the Corvette forum. The example I use is figure average driver maybe puts on 10,000 miles a year and figure lousy mileage like 15 mpg. That works out to be about 700 gallons. Even if premium is 50 cents more a gallon that ends up $350 more per year. Is that worth fretting about?
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11-26-23 | 02:12 PM
#6
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I have seen this question posed on forums for the various cars I have owned in the past including even the Corvette forum. The example I use is figure average driver maybe puts on 10,000 miles a year and figure lousy mileage like 15 mpg. That works out to be about 700 gallons. Even if premium is 50 cents more a gallon that ends up $350 more per year. Is that worth fretting about?
11-26-23 | 03:51 PM
#8
Racer
Joined: Aug 2011
Posts: 1,617
Likes: 668
The "atkinson" cycle engine used in the hybrid is very high static compression ratio engine. To get the max power out of a typical high compression engines often requires premium fuel to prevent damage from uneven fuel burning due to knocking (aka denotation, pre-ignition, etc). However the whole premise behind atkinson cycle engines is to limit air intake into the cylinder (sort of like an anti-turbo). Less air charge, less fuel, some less power but more room for complete combustion, so much more efficient and less emissions, hence being favoured in hybrid vehicles where electric drive can assist power. This reduced air charge actually reduces the actual compression ratio in most situations other than under full throttle. In normal everyday conditions regular will do perfectly fine and get you most miles for the buck. If you have your foot to the floor occasionally, regular will still be fine as the engine computer will limit knock by backing off power a tad. If however you have your foot to the floor often, premium will let the engine eek out extra power without the computer imposing its limits when using regular fuel to prevent knock.
PS it is not the same motor as the gas RAV4 or NX250. Same family though, but cylinder head is different. Also, Toyota tends to tune down compared with Lexus. Take for example the NX350 engine, T24A turbo requires premium in NX while the same engine in the Highlander does not, because the Toyota version is tuned down to make less power.
PS it is not the same motor as the gas RAV4 or NX250. Same family though, but cylinder head is different. Also, Toyota tends to tune down compared with Lexus. Take for example the NX350 engine, T24A turbo requires premium in NX while the same engine in the Highlander does not, because the Toyota version is tuned down to make less power.
11-26-23 | 04:14 PM
#9
Racer
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what is the main purpose of premium gas? To retard the spark and prevent premature detonation, i.e. knocking. If you car is not knocking then premium give you no gain.( okay maybe 5-7 Hp woopie 
) so instead of 240 hp-7 Hp= 233Hp you get a gain of 3 %
Peace to All . If you want premium gas go for it.
YMMV,
MidCow3 ( my 7th Toyota/Lexus hybrid, driven them flawlessly on regular for 13 years )
) so instead of 240 hp-7 Hp= 233Hp you get a gain of 3 %Peace to All . If you want premium gas go for it.
YMMV,
MidCow3 ( my 7th Toyota/Lexus hybrid, driven them flawlessly on regular for 13 years )
11-26-23 | 04:29 PM
#10
Racer
Joined: Apr 2015
Posts: 1,393
Likes: 613
From: Ontario
what is the main purpose of premium gas? To retard the spark and prevent premature detonation, i.e. knocking. If you car is not knocking then premium give you no gain.( okay maybe 5-7 Hp woopie ) so instead of 240 hp-7 Hp= 233Hp you get a gain of 3 %
Peace to All . If you want premium gas go for it.
YMMV,
MidCow3 ( my 7th Toyota/Lexus hybrid, driven them flawlessly on regular for 13 years )
) so instead of 240 hp-7 Hp= 233Hp you get a gain of 3 %Peace to All . If you want premium gas go for it.
YMMV,
MidCow3 ( my 7th Toyota/Lexus hybrid, driven them flawlessly on regular for 13 years )
11-26-23 | 04:34 PM
#11
Racer
Joined: Aug 2011
Posts: 1,617
Likes: 668
anti-turbo ??
Regular works fine for most people and I don't think there is a need to enforce Premium or Regular. If regular works for you great. No need to tell people what to use. @Droid13 reply is well written and very neutral.
Peace to all, Use whatever gas you want.
YMMV,
MidCow3
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11-26-23 | 05:36 PM
#13
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From: WA
Interesting how invested some folks can get over this issue. Droid13 was being explanatory and prefaced the term 'anti-turbo' with the words 'sort of like an' which was helpful to my understanding which is why I started the thread. And thank you lsft for the customary level headed observations. I don't need to be told by other owners to use whatever fuel I want--I already knew that as does everyone else. If you want to run popcorn oil that's your choice. Just not Lexus recommended.
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lsft (11-26-23)
11-26-23 | 07:27 PM
#14
Racer
Joined: Aug 2011
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YMMV,
MidCow3
P.S.- This is too much . Driving up to my cabin in the woods to relax
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fitiam4me (11-27-23)
11-26-23 | 09:14 PM
#15
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From: WA
Madcap---it is not MUCH more cost effective if you don't define "much more." It's relative. It's a cost benefit analysis. Which turns on a host of variables. Hey--you like being a regular pumper. Fine. Pump away. It's okay. Choice. Yours and others. We all choose. This thread was not about what is the 'Smarter" choice. It was about why Lexus recommends premium.This thread was not about choosing sides and not being able to let go. But let me suggest if your comments aren't about why Lexus recommends premium that you let it go.
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Billst (11-27-23)