What fuel grade is everyone using on their 2012-2015 RX?
04-29-12, 09:45 PM
#46
Well
On previous RXs they told me I could use regular. After 4 years the 400h started getting bad mileage and poorer performance and I had to switch to premium even though I always used top tier gas. But on the 2010 they said I really needed to use premium (same service advisor). Ironically, at my last trip to the Shell station the attendant was surprised when I requested premium. Hmm I wonder what other RX owners do. There are zillions in town,
I have worked it both ways with no problems except MORE or LESS power and MORE or LESS gas mileage...driving drone powered LIncolns in 2005 and getting an almost drivable car with Premium in it.....and if I don't want to push my Corvette powered GTO, I can put in regular in a pinch and just get less of both horsepower and gas mileage!!!!!!!
Last edited by dctex99; 04-29-12 at 09:49 PM.
04-29-12, 10:13 PM
#47
Lexus Test Driver
the DEBATE about decrease/increase in horse power.. and some myths decrease in milage will go on for years.
However, nothing can beat personal experience.
I have been using regular unleaded (87 octane) on my 2011 for more than 6 months now.
i haven't noticed any knock nor pinging on the engine.
i normally get an average of 22 combined.
here's my highway milage. 24.7mpg running on 70's
personally, i don't feel the decrease in horse power either.
http://flic.kr/p/bRNY2n
However, nothing can beat personal experience.
I have been using regular unleaded (87 octane) on my 2011 for more than 6 months now.
i haven't noticed any knock nor pinging on the engine.
i normally get an average of 22 combined.
here's my highway milage. 24.7mpg running on 70's
personally, i don't feel the decrease in horse power either.
http://flic.kr/p/bRNY2n
Last edited by markrivers; 04-29-12 at 10:25 PM. Reason: uploading picture
04-30-12, 07:58 PM
#49
the DEBATE about decrease/increase in horse power.. and some myths decrease in milage will go on for years.
However, nothing can beat personal experience.
I have been using regular unleaded (87 octane) on my 2011 for more than 6 months now.
i haven't noticed any knock nor pinging on the engine.
i normally get an average of 22 combined.
here's my highway milage. 24.7mpg running on 70's
personally, i don't feel the decrease in horse power either.
http://flic.kr/p/bRNY2n
However, nothing can beat personal experience.
I have been using regular unleaded (87 octane) on my 2011 for more than 6 months now.
i haven't noticed any knock nor pinging on the engine.
i normally get an average of 22 combined.
here's my highway milage. 24.7mpg running on 70's
personally, i don't feel the decrease in horse power either.
http://flic.kr/p/bRNY2n
In our Audi Q5 I can feel the difference if using regular-it requires premium gas (minimum octane 91)-so now we put 89 mid grade, and no knocking/pinging either.
I feel that at the highway speeds, when acceleration can be critical and safety factor, premium gas may help, but in the city I do not feel much difference. I am not trying to save money because there woul.d be maybe $130-150 difference on gas moneyspent in a year...
05-01-12, 06:17 AM
#50
Lexus Champion
Thread Starter
The premium vs. regular fuel discussion keeps coming up over on the ES forum as well, although it's slowed down a bit.
You can't go wrong using either grade. Use what you are comfortable with and thngs will be fine.
You can't go wrong using either grade. Use what you are comfortable with and thngs will be fine.
05-01-12, 11:16 PM
#51
Lexus Test Driver
However, compared to the other 1,000 threads out there,
THIS thread is asking for the "Reverse"
a 2012 RX 350 with a recommended Regular (87 octane) owner is asking if he can get more Horsepower by putting in Premium.
anyway, i doubt if more than half of RX 350 owners go over a 5,000 rpm anyway, but to each his own.
05-02-12, 05:40 AM
#52
I've visited forums for every car I've ever owned and this same discussion inevitably comes up in one form or another.
"Do I REALLY have to use premium?"
"Will I get better gas milage if I use premium?"
"Will I get more horsepower if I use premium?"
"Will my car last longer if I use premium?"
I think the best advice is fill your car with premium for a few tanks. Then use lower grade for a few tanks.
If you don't notice a difference in performance or mileage then don't pay the extra for premium fuel. If you do notice a difference then try mid-grade and see if that works.
Then just buy the cheapest gas that works in your car.
Though there's a school of thought recently brough out on the BMW forum that says if you're spending $50k or more on a car (especially a performance car) are you just being a cheapskate trying to save a couple bucks on a tank of gas.
"Do I REALLY have to use premium?"
"Will I get better gas milage if I use premium?"
"Will I get more horsepower if I use premium?"
"Will my car last longer if I use premium?"
I think the best advice is fill your car with premium for a few tanks. Then use lower grade for a few tanks.
If you don't notice a difference in performance or mileage then don't pay the extra for premium fuel. If you do notice a difference then try mid-grade and see if that works.
Then just buy the cheapest gas that works in your car.
Though there's a school of thought recently brough out on the BMW forum that says if you're spending $50k or more on a car (especially a performance car) are you just being a cheapskate trying to save a couple bucks on a tank of gas.
05-02-12, 07:39 AM
#54
My Dad, who understood the internal combustion engine better than most, swore there was no impact to engine output due to octane rating. I believed him then, and still do.
However, that was before engines were managed by computers and sensors. It is my understanding that sensors monitor many aspects of your engine many times per second, including knock, mixture, and timing. Am I wrong in assuming that engine management will make adjustments in these areas, to make the engine to run as efficiently as possible without creating knock or excessive heat? In my admittedly twisted sense of logic, efficiency translates into more power using less fuel. Using a fuel with a higher octane rating, the computer can run the engine leaner, and with more timing (advance?) without introducing knock. Leaner and more timing means more power available, and better mileage, right?
It's not the higher octane that improves power, it's the adjustments you can make to increase the efficiency of the engine when you have more knock inhibitors (higher octane).
Does this logic make sense to anyone besides me?
However, that was before engines were managed by computers and sensors. It is my understanding that sensors monitor many aspects of your engine many times per second, including knock, mixture, and timing. Am I wrong in assuming that engine management will make adjustments in these areas, to make the engine to run as efficiently as possible without creating knock or excessive heat? In my admittedly twisted sense of logic, efficiency translates into more power using less fuel. Using a fuel with a higher octane rating, the computer can run the engine leaner, and with more timing (advance?) without introducing knock. Leaner and more timing means more power available, and better mileage, right?
It's not the higher octane that improves power, it's the adjustments you can make to increase the efficiency of the engine when you have more knock inhibitors (higher octane).
Does this logic make sense to anyone besides me?
05-02-12, 08:46 AM
#55
Sorry it really doesn't
My Dad, who understood the internal combustion engine better than most, swore there was no impact to engine output due to octane rating. I believed him then, and still do.
However, that was before engines were managed by computers and sensors. It is my understanding that sensors monitor many aspects of your engine many times per second, including knock, mixture, and timing. Am I wrong in assuming that engine management will make adjustments in these areas, to make the engine to run as efficiently as possible without creating knock or excessive heat? In my admittedly twisted sense of logic, efficiency translates into more power using less fuel. Using a fuel with a higher octane rating, the computer can run the engine leaner, and with more timing (advance?) without introducing knock. Leaner and more timing means more power available, and better mileage, right?
It's not the higher octane that improves power, it's the adjustments you can make to increase the efficiency of the engine when you have more knock inhibitors (higher octane).
Does this logic make sense to anyone besides me?
However, that was before engines were managed by computers and sensors. It is my understanding that sensors monitor many aspects of your engine many times per second, including knock, mixture, and timing. Am I wrong in assuming that engine management will make adjustments in these areas, to make the engine to run as efficiently as possible without creating knock or excessive heat? In my admittedly twisted sense of logic, efficiency translates into more power using less fuel. Using a fuel with a higher octane rating, the computer can run the engine leaner, and with more timing (advance?) without introducing knock. Leaner and more timing means more power available, and better mileage, right?
It's not the higher octane that improves power, it's the adjustments you can make to increase the efficiency of the engine when you have more knock inhibitors (higher octane).
Does this logic make sense to anyone besides me?
05-02-12, 10:10 AM
#56
http://en.wikipedia.org/wiki/Octane_rating
Excerpt from above wiki article:
Many high-performance engines are designed to operate with a high maximum compression, and thus demand fuels of higher octane. A common misconception is that power output or fuel efficiency can be improved by burning fuel of higher octane than that specified by the engine manufacturer. The power output of an engine depends in part on the energy density of the fuel being burnt. Fuels of different octane ratings may have similar densities, but because switching to a higher octane fuel does not add more hydrocarbon content or oxygen, the engine cannot develop more power.
Excerpt from above wiki article:
Many high-performance engines are designed to operate with a high maximum compression, and thus demand fuels of higher octane. A common misconception is that power output or fuel efficiency can be improved by burning fuel of higher octane than that specified by the engine manufacturer. The power output of an engine depends in part on the energy density of the fuel being burnt. Fuels of different octane ratings may have similar densities, but because switching to a higher octane fuel does not add more hydrocarbon content or oxygen, the engine cannot develop more power.
05-02-12, 04:38 PM
#57
we are really getting into "the weeds" on this matter....I think this thread will go for ever, I even "dare" to mention the money factor is buying regular gas to another poster and it was like sticking my head out the window of a car......wham!!!...got hit by a tree branch!!!!! ....I am a quick learner (it comes with age).....I "closed" THAT window quickly...lol
05-02-12, 06:54 PM
#58
I'm loving the different opinions to my question about the horsepower and premium. I would love to pose this to the Lexus engineer who detuned the engine causing the loss of 5 horsepower. I understand that the 2013 gets the horsepower back to 270. I wonder how they are doing that and still running regular.
Last edited by Marqevans; 05-02-12 at 07:08 PM. Reason: Spelling
05-02-12, 08:23 PM
#59
...and his answer will probably be..."the computer does it".....but here you really open the proverbial "pandora's box"...good discussion..and to be honest I did not see much "blood"...lol
05-02-12, 08:35 PM
#60
Lexus Test Driver
Well, i can say buying a luxury vehicle is a NOT a sign of being practical..
so it's really hard for most members to understand the "Savings" of using a Regular (87) on a vehicle that Recommends "REGULAR", which is the MAIN Focus of this thread.
Even though the Engineers recommend an every 10,000 mile change oil, No one's stopping anyone from doing it every 3,000 miles ( another debatable issue)
i don't know about you guys, but i ONLY use Evian or Volvic water to wash my Range Rover and the RX 350. =)
Seriously, do what you're more comfortable with.
so it's really hard for most members to understand the "Savings" of using a Regular (87) on a vehicle that Recommends "REGULAR", which is the MAIN Focus of this thread.
Even though the Engineers recommend an every 10,000 mile change oil, No one's stopping anyone from doing it every 3,000 miles ( another debatable issue)
i don't know about you guys, but i ONLY use Evian or Volvic water to wash my Range Rover and the RX 350. =)
Seriously, do what you're more comfortable with.
