2008 RX-350 Fuel Octane Rating
Lexus Champion
Joined: Aug 2007
Posts: 4,507
Likes: 38
From: Bethlehem Twsp. Pennsylvania
Driver School Candidate
Joined: Sep 2008
Posts: 32
Likes: 0
From: WI
Maybe because Lexus engineers recommend premium.
Just use 87 and be happy.
My RX is leased.
I use 89 and an occasional 93 fill.
My GS is a purchase and I use Shell 93.
Don't tell me you would use 87 in a GS.
Even you wouldn't.
There isn't a Toyota model with the exact same engine.
Just use 87 and be happy.
My RX is leased.
I use 89 and an occasional 93 fill.
My GS is a purchase and I use Shell 93.
Don't tell me you would use 87 in a GS.
Even you wouldn't.
There isn't a Toyota model with the exact same engine.
Can't comment on the GS, don't know anything about it.
As for being "happy", I'll be happy using premium IF that's really what it requires. If regular is all it needs I'd rather not waste the money on premium. Yes I know it's only $4 a tankful and yes I can afford it, but I don't like wasting money for no good purpose.
Here's the reply from Lexus...
"Per your inquiry, the Lexus RX 350 has a higher compression motor than the Toyota Highlander, which requires premium gasoline for optimum engine performance. If Premium gasoline is not available, you may use unleaded gasoline with an Octane Rating as low as 87. The use of such gasoline will not allow your vehicle to operate at optimum engine performance and may also cause persistent heavy knocking. For more information, please refer to your Owner's Manual or your local Lexus dealership."
This does not clear up anything since the published data shows they both have the SAME compression. I followed up by asking for the compression ratio of each.
Driver
Joined: Jan 2007
Posts: 118
Likes: 0
From: Miami, Surburb of Havana :/ :/
Well if you use 87 and the manual says premium and if premium is available in your area and your knock causes engine damage.....bet you a price of a new car, Lexus will have your gas tested and determine if you ran premium, if not, YOU would be held responsible as the warranty is void. Is it worth the hassle? I can tell you the extra for premium you paid in five years wont even dent any major engine damage costs.
Lexus Champion
Joined: Aug 2007
Posts: 4,507
Likes: 38
From: Bethlehem Twsp. Pennsylvania
It seem`s the bottom line is fairly simple,if you want peak performance,your best fuel millage,use the premium.If your not concerned about the performance,use regular. I just don`t like the idea of my engine running around on retard timing.That cant be good.Higher exhaust gas temp. etc.
Last edited by lexus114; Sep 15, 2008 at 11:23 AM.
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It seem`s the bottom line is fairly simple,if you want peak performance,your best fuel millage,use the premium.If your not concerned about the performance,use regular. I just don`t like the idea of my engine running around on retard timing.That cant be good.Higher exhaust gas temp. etc.
Driver School Candidate
Joined: Sep 2008
Posts: 32
Likes: 0
From: WI
It seem`s the bottom line is fairly simple,if you want peak performance,your best fuel millage,use the premium.If your not concerned about the performance,use regular. I just don`t like the idea of my engine running around on retard timing.That cant be good.Higher exhaust gas temp. etc.
The bottom line is not that simple. If the engine only needs regular, like the (apparently) identical Highlander engine does, then running premium gains you nothing.
BTW, high EGT is good. Peak power occurs at peak EGT.
Lexus Champion
Joined: Jan 2003
Posts: 2,754
Likes: 6
From: Colorado
My old GM PoS used to ping like a mo fo. Pinging is an engine defect that carmakers don't want to fix during the warranty period. So they call it normal. Typically it's caused by the engine not fully burning the fuel, leaving carbon deposit behind.
Pole Position
Joined: Dec 2003
Posts: 3,283
Likes: 63
From: FL
Not to rain on your parade but I also own an 04 Highlander Limited and it gets better mileage with premium. About 1.5 mpg better similar to my RX330. So continue on with your discussion but I get better performance and mileage with premium. That's all I need to know to make my choice.
Lexus Champion
Joined: Aug 2007
Posts: 4,507
Likes: 38
From: Bethlehem Twsp. Pennsylvania
Oh boy,no more comments on this anymore. But I will ask you this AV8R, how can negative timing be any good at all to an internal combustion engine? Please explain that to me? It defies the law of physics on itself,meaning less power,etc. If Lexus truely did map their ecms to run best on premium,lets not forget to mention the high compression(I know you can use regular)you can bet,it will run its best on higher octane fuel.Or,it will retard timing,and not perform like it was designed to.
Last edited by lexus114; Sep 16, 2008 at 07:21 AM.
CL Community Team
Joined: Apr 2004
Posts: 17,337
Likes: 213
From: Miami, Florida
I should let you all know that I in my RX300 effective a Sunday I began a trial run on 87 octane Chevron. Now, I do have a few things like a modified exhaust and especially the crankcase vent filters (that do a have a direct effect on octane) in order to measure mpg and I'll be able to know about other performance based on experience. Thus far after an ECU reset via the battery, the vehicle doesn't quite pack the punch that it does on acceleration, but no pinging or other issue otherwise. Actual time MPG appears to be the same, but I am waiting to do a bit of expressway/highway mileage tonight to verify. This is the first time in a long time (except for some brief tests in Mexico) that I have done this.