RX - 3rd Gen (2010-2015) Discussion topics related to the 2010 - 2015 RX350 and RX450H models

Another fuel question (perhaps a dumb one...)

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Old 02-27-10, 04:11 PM
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DNC
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Originally Posted by lalin
My question is more philosophical than economical. My point is that Toyota recommends regular fuel for all the other V6 engines that are pretty much the same one as on the RX.
Yes, I wonder what could be different?
Old 02-27-10, 05:32 PM
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Marqevans
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Joe's gas station probably is buying it's gas from Shell or Chevron.
Old 02-27-10, 05:43 PM
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Default Premium versus Regular

Originally Posted by DNC
I know this subject comes up time after time but I fail to see the big deal with just running premium gas as the manual recommends. I don't see how someone can be talked into buying a $50K car and yet they resist buying premium fuel. Are car sales people that good??
I agree the additional cost isn't that much. Especialy now in the Midwest when gas was $2.00 per gallon we were paying $2.20 for premium or 10% more. Now that gas is near $3.00 we still have the same $.20 difference so now it is only 6.5% more for premium.
Old 03-01-10, 08:09 AM
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WHY YOU SHOULD USE THE RECOMMENDED OCTANE:

gas molecules are hydrocarbon chains, and the lower the octane the lower the average length of the hydrocarbons is going to be. Short hydrocarbons are broken or 'burned' easier than langer ones found in higher octanes. Putting super in a lower compression engine that does not require it will lead to accelerated carbon build up as the engine will not burn the average longer (stronger) hydrocarbons as effectively.

The reason why you can, however, put regular in a car that needs super is that the compression will effectively burn the average shorter chain hydrocarbons. Timing via the knock sensor is adjusted as injection of a more easily combustable fuel at the same timing would cause early detonation (pinging).

Lastly, the on average shorter hydrocarbon chains contain less energy, and as such you will experience lower economy (more fuel must be burned to get the same energy output)

So if you put super in a car that needs regular you are actually wasting money and carboning up your engine. If you drive a lexus you can put whatever fuel you want, however if it is anything less than super there will be poorer fuel economy and lower power.

Check the stats of the camry V6, venza V6 and rx v6. All run a compression ratio of 10.8 to 1. The extra hp for the lexus comes down to timing/tuning and higher octane fuel
Old 03-01-10, 10:44 AM
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Originally Posted by dr_p
WHY YOU SHOULD USE THE RECOMMENDED OCTANE:

gas molecules are hydrocarbon chains, and the lower the octane the lower the average length of the hydrocarbons is going to be. Short hydrocarbons are broken or 'burned' easier than langer ones found in higher octanes. Putting super in a lower compression engine that does not require it will lead to accelerated carbon build up as the engine will not burn the average longer (stronger) hydrocarbons as effectively.

The reason why you can, however, put regular in a car that needs super is that the compression will effectively burn the average shorter chain hydrocarbons. Timing via the knock sensor is adjusted as injection of a more easily combustable fuel at the same timing would cause early detonation (pinging).

Lastly, the on average shorter hydrocarbon chains contain less energy, and as such you will experience lower economy (more fuel must be burned to get the same energy output)

So if you put super in a car that needs regular you are actually wasting money and carboning up your engine. If you drive a lexus you can put whatever fuel you want, however if it is anything less than super there will be poorer fuel economy and lower power.

Check the stats of the camry V6, venza V6 and rx v6. All run a compression ratio of 10.8 to 1. The extra hp for the lexus comes down to timing/tuning and higher octane fuel
Informative! Thanks for the input!
Old 03-01-10, 03:00 PM
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BHart882
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Originally Posted by ziggy1
Informative! Thanks for the input!
Yeah ditto, great post dr_p.

If my baby prefers premium, she's gonna get it.
Old 03-01-10, 04:34 PM
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CharlesSch
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With all due respect, if you cannot afford to purchase premium unleaded, then you probably should not be buying a $45k vehicle.
Old 03-01-10, 06:20 PM
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Originally Posted by CharlesSch
With all due respect, if you cannot afford to purchase premium unleaded, then you probably should not be buying a $45k vehicle.
Charles, you are right, that is the bottom line. A fellow I know who has been a mechanic for Mercedes, BMW, and some domestic dealership I can't remember, is now a Lexus mechanic. He told me Lexus owner's are the worst when it comes to not wanting to part with money to properly maintain their cars, and RX owners seem to be the worst of the Lexus pack. He has oil change stories that are just crazy.
Old 03-04-10, 07:57 AM
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Speaking of octane. Does anyone know why Sunoco discontinued 94 octane?
Old 03-04-10, 04:42 PM
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Originally Posted by AVIA1541
Speaking of octane. Does anyone know why Sunoco discontinued 94 octane?
Where have you been, they stop selling it like 4 years ago.
Old 03-04-10, 06:55 PM
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Where have you been, they stop selling it like 4 years ago.

I am aware how long it's been unavailable, but that wasn't the question #$%@
Old 03-04-10, 08:23 PM
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Originally Posted by AVIA1541
Speaking of octane. Does anyone know why Sunoco discontinued 94 octane?
Too costly for them because of the transportation costs. Oil companies piggy back on each others tanker fleets and use each others distribution centers to keep the cost down and profits up. for example Shell would supply all stations in a geographic area no matter what the signs on top of the stations say (Exxon, Chevron etc) and vice versa. they were the only one with 94 octane so they had to bare the whole transportation cost themselves. Which proved too costly!
Old 03-05-10, 09:40 AM
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The ecm is calibrated for premium fuel.
Old 03-05-10, 09:52 AM
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Originally Posted by SALTY2
Too costly for them because of the transportation costs. Oil companies piggy back on each others tanker fleets and use each others distribution centers to keep the cost down and profits up. for example Shell would supply all stations in a geographic area no matter what the signs on top of the stations say (Exxon, Chevron etc) and vice versa. they were the only one with 94 octane so they had to bare the whole transportation cost themselves. Which proved too costly!
If you are saying BP/Amoco gas is the same as Exxon (just as an example) that is not true here in the US.
Old 03-05-10, 10:32 AM
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Originally Posted by AVIA1541
Where have you been, they stop selling it like 4 years ago.

I am aware how long it's been unavailable, but that wasn't the question #$%@
Ultra 94 uses MTBE which was restricted by the EPA.

Last edited by wyau01; 03-05-10 at 11:33 AM.


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