panjfj

i guess i just realize that RX350 and RX450h have different fuel requirements.

tus

The 2GR-FXE is the version of the GR engine that is used in the RX 450h and requires 91. The RX 350 has only needed 87 since 2011.

Here's a chart of which one needs what fuel:
http://lexus2.custhelp.com/app/answe...xus-vehicle%3F

salimshah

Engines may have same displacement but are tuned to run differently.

Salim

Freds430

This is probably the most heated debate on these forums. Do whatever makes you comfortable. I use 87 octane in our 2015 RX450h. Experimenting with the other two levels, I have noticed zero difference in gas mileage or performance. I have used 87 in cars that have required premium for over a million miles and have not had one problem.
A previous post of mine on the subject.
I always revert back to two MIT graduates that are car mechanics who had a syndicated radio show called Car Talk for 35 years.
http://www.cartalk.com/content/premi...egular-0#myth4

From the USA Today:
The only modern engines that should really need premium are those with superchargers, which force-feed fuel into the cylinders. "You're driving along and just tramp the gas and the knock sensor cannot sense the knock fast enough in some cases," because the supercharger boosts pressure so fast, says Bob Furey, chemist and fuels specialist at General Motors.

Burning regular when the owner's manual specifies premium won't void the warranty, nor damage the engine, even the most finicky automakers say. "You're giving up perhaps just a little bit of performance that a customer wouldn't really even notice, it's so slight," says Furey.

mcomer

The "350" designation covers a couple different configurations:

2007 - 2010 RX350's had 270 HP/251 lb/ft using Premium (note: 5 speed became 6 speed in 2010)
2011 - 2015 RX350's had 275 HP/257 lb/ft using Regular
2016 - 2018 RX350's have 292 HP/265 lb/ft using Regular (note: F-Sport 8 speed became std for all in 2016)

2007 - 2011 ES350's had 272 HP/254 lb/ft using Premium
2012 - 2018 ES350's had 268 HP/248 lb/ft using Regular (note: body changed in 2013)

2007 - 2011 GS350's had 303 HP/274 lb/ft using Premium
2013 - 2017 GS350's had 306 HP/277 lb/ft using Premium (trivia note - no 2012 GS's)
2018 - GS350 have 311 HP/280 lb/ft using Premium

2007 - 2018 IS350's have 306 HP/277 lb/ft using Premium
2016 - 2018 IS300's have 255 HP/236 lb/ft using Premium (not so trivial - 3.5L ?!)

2010 - 2015 RX450h had 295 HP (torque N/A) on Premium (displacement - 3.5L)
2016 - 2018 RX450h has 308 HP (torque N/A) on Premium (displacement - 3.5L)

2007 - 2011 GS450h had 340 HP (torque N/A) on Premium (displacement - 3.5L)
2013 - 2018 GS450h has 338 HP (torque N/A) on Premium (displacement - 3.5L)

2018 LC500h has 354 HP (torque N/A) on Premium (displacement - 3.5L) Multistage (4 speed) CVT
2018 LS500 will have 416 HP/442 lb/ft on Premium (displacement - 3.5L) 10 speed transmission

Because of rating changes in 2008 and 2017 to EPA procedures
I did not clutter up this page with asterisks and arrows!

raytseng

above isn't correct.

The 2011 RX350 on premium tested at 275 / 257
http://pressroom.lexus.com/article_d...rticle_id=2669

when TESTING switched to Regular 2012-2015 it tested at 270 / 248ft-lbs
http://pressroom.lexus.com/releases/...duct+specs.htm

This was a cosmetic refresh for 3rd gen RX, and it is just TESTING (and marketing) that changed, and unlikely engine or tuning was updated. I take the above as the definitive evidence of what to expect between regular and premium in the RX350 3rd gen.

The other data points are different models with different engines, engine tunings, upgrades so those aren't very good comparison points as the 2011RX350 vs 2012 RX350

riredale

My take on this perennial issue is simple--in the old days, if you ran on 87 and could hear pinging (sounded exactly like marbles rattling in a tin can) when you put your foot into it then you needed 91 octane--or you could reduce the timing a bit. What would you lose by retarding timing? A bit of horsepower.

Now that no longer holds; contemporary engines AUTOMATICALLY listen for pinging and reduce the timing for you. What do you lose? A bit of horsepower.

The marketing department no doubt wants the highest horsepower numbers possible--hence the mention of 91 octane fuel.

raytseng

To be specific, regular->premium; you gain 5 horsepower(1.85%) and 9 torque (3.63%) [based on testing numbers above]

riredale's quote isn't always true; as you see from 2011->2012 Sales and Marketing did exact opposite and said REGULAR fuel is more important for sales than max HP.

ukrkoz

Our 2011 is clearly saying Premium Unleaded Fuel ONLY on gas tank door. M<anual says regular fuel can be used ONLY as emergency and needs to be replaced with premium as soon as possible.
My 2012 Highlander hybrid, which is same power train as RX hybrid models, is REGULAR gasoline as that engine is souped down on power and has lower compression. Higher compression=higher octane.2GR-FXE

Atkinson cycle, VVT-i, uses cooled EGR system.

For the Lexus RX 450h, the compression ratio was 12.5 to 1. For the Lexus GS 450h, the compression ratio was 13.0 to 1.[8]

Applications (calendar years):

• 2010 Lexus RX 450h, (GYL10/15/16), without D-4S (conventional multiport indirect injection) 183 kW (245 bhp)
• 2010 Toyota Highlander Hybrid, without D-4S (conventional multi-port indirect injection) 183 kW (245 bhp)
• 2012 Lexus GS 450h (GWL10), with D-4S (both multi-port indirect and direct injection) 218 kW (292 bhp)
• 2013 Toyota Crown Majesta

I actually popped the hood and checked. HiHy DOES have 2GR-FXE engine there , for 2012, which is not mentioned in the above chart. Also, WHY Lexus tells you in reference linked to to use 91 octane on SAME engine HiHy is using 87 on beats me.
Makes one wonder though. But no, if you have 2GR-FXE - it's 87 octane.

Skier76

Our 2009 IS250 requires premium due to the direct injection.

Using premium in an RX every fill-up may be overkill. But I view it in a similar way to adding a bottle of injector cleaner every so often. Higher octane fuels often have more detergents in the mix. So a tankful of premium isn't a bad thing here or there.

Cocal

It's the perennial story, people read what they want in the manual. It says not to go below 87 (implying you can go above) as damage may occur, but why be so close to the limit? Why not go at 89 at least you have some room to wiggle, also the octane posted is an average, so you may be below that or above that in some cases.

UZ214

Gas being cheap these days, early last week I treated the RX with 93. To be honest I got the gas for the my SCAG mower and also used the same for RX. Took by boys to MTB trails last weekend and today I was out in the morning couldn't help but notice how smooth the RX feels. Pick up from red light is better and just seems less noise, then I remembered I used better gas.

The car has 170k and it drives like a brand new car..amazing. Maybe its just in my head since not not driving a lot these days..

iolmaster

iTrader: (1)

Guys, Anyone that reads this, do not believe it. 93 octane is not better and will not impart any advantage to a car that is not designed for the higher octane. This is pure placebo.
I can't believe that people still think this is true.

UZ214

Top Tier gas isn't better for your engine? to add I usually put in 93 for my mowers, they seem to start right away after storage compared to regular.

https://www.consumerreports.org/car-...h-extra-price/

Non

"Top Tier" does not mean premium grade or 93 octanes.
Top Tier is a particular brand of gasoline.
If a gas station claims to sell Top tier gas, all of the grades they offer, including regular, premium and diesel, are supposed to be "Top Tier." That is what the linked article says, if you read it carefully.
I know that the "Top Tear" label is not just a marketing gimmick, the gas has more detergents. I always try to buy gas from a Top tier gas station whenever possible, but I always buy regular.