View Poll Results: What gas do you put into your 2RX?
Premium
0
0%
Medium
0
0%
Regular Unleaded
0
0%
Voters: 0. You may not vote on this poll
Do you need Premium Gas in the 2RX (merged discussion threads)
03-20-17, 08:58 AM
#631
Racer
I can't remember the last time I had a car where I was forced to run premium in it. I use the cheapest gas I can find. The computer adjusts the timing so the engine doesn't ping. Every once in a while I will fill up with premium and I can detect a difference in performance. But it is not that great so I don't make a habit of it.
05-09-19, 12:54 PM
#633
Driver School Candidate
Older model are recommended to use premium gas while newer model could use regular gas. However the price is 12% difference. I am wondering if I could use regular instead of premium gas.
05-09-19, 02:09 PM
#634
My 05 RX330 recommends regular unleaded. Read your manual. If it requires premium then use it. Or, if it requires regular, and you like to give extra money to the oil companies, buy it. 
Seriously I have never noticed any MPG or power improvement with Premium.
Seriously I have never noticed any MPG or power improvement with Premium.
05-09-19, 04:37 PM
#635
Advanced
2004 RX330 - 242,000 miles all on 85 octane (mountains - same as 87 at other elevations). I have run a couple of tanks of premium and never noticed any difference in mpg, hp, etc.
Last edited by cdnewton; 05-09-19 at 07:03 PM. Reason: wording
05-09-19, 07:01 PM
#636
Racer
From the 2007 RX Owners Manual, Section 6-1 Specifications, page 399, titled "Fuel information":
Your vehicle must use only unleaded gasoline. Premium unleaded gasoline with an octane rating of 91 (Research Octane Number 96) or higher required for optimum engine performance. At minimum, the gasoline you use should meet the specifications of ASTM D4814 in the U.S.A. and CGSB3.5-M93 in Canada.
* Fuel tank opening for unleaded gasoline - To help prevent incorrect fueling, your Lexus has a fuel tank opening that only accommodates the special nozzle on unleaded fuel pumps.
* If premium gasoline is not available - If 91 rating gasoline cannot be obtained, you may use unleaded gasoline with an octane rating as low as 87 (Research Octane Number 91).
* If your engine knocks
Consult your Lexus dealer.
You may occasionally notice light knocking for a short time while accelerating or driving uphill. This is normal and there is no need for concern.
* Gasoline quality - In very few cases, driveability problems may be caused by the brand of gasoline you are using. If driveability problems persist, try changing the brand of gasoline. If this does not correct the problem, consult your Lexus dealer.
Your vehicle must use only unleaded gasoline. Premium unleaded gasoline with an octane rating of 91 (Research Octane Number 96) or higher required for optimum engine performance. At minimum, the gasoline you use should meet the specifications of ASTM D4814 in the U.S.A. and CGSB3.5-M93 in Canada.
* Fuel tank opening for unleaded gasoline - To help prevent incorrect fueling, your Lexus has a fuel tank opening that only accommodates the special nozzle on unleaded fuel pumps.
* If premium gasoline is not available - If 91 rating gasoline cannot be obtained, you may use unleaded gasoline with an octane rating as low as 87 (Research Octane Number 91).
* If your engine knocks
Consult your Lexus dealer.
You may occasionally notice light knocking for a short time while accelerating or driving uphill. This is normal and there is no need for concern.
* Gasoline quality - In very few cases, driveability problems may be caused by the brand of gasoline you are using. If driveability problems persist, try changing the brand of gasoline. If this does not correct the problem, consult your Lexus dealer.
05-10-19, 05:07 PM
#637
2006 RX330 AWD 238,000km on 87 regular all the time since brought used at 100,000km , Never got engine issues and still has good MPG with factory A/F R and O2.
Engine runs smooth and quiet with dino oil 8,000km change interval always. all spark plus are good shape when changed out at 180,000km.
Engine runs smooth and quiet with dino oil 8,000km change interval always. all spark plus are good shape when changed out at 180,000km.
05-10-19, 05:53 PM
#638
Racer
I mostly run premium in my 07 rx350. But I have on a few occasions run regular but then noticed I wasnt getting the average of 22-24ish mpg that I had been getting using premium
05-10-19, 10:27 PM
#639
you get more miles per tank (and better performance) with premium fuel. If you work out cost per mileage the difference is very small $. premium fuel = higher $ to fill up the tank, but greater distance, with better performance.
05-11-19, 08:19 AM
#640
Advanced
My comments refer to the "second generation" RX with the 3.3L V6, I believe the 3.5L V6 is also categorized in the second generation and may be different.
2004 RX330 owners manual on octane rating:
Select Octane Rating 87 (Research Octane Number 91) or higher. For improved vehicle performance, the use of premium unleaded gasoline with an Octane Rating of 91 (Research Octane Number 96) or higher is recommended.
There is a big difference between 'required' and 'recommended'.
Finally, the 3.3L V6 is the same engine used in the Highlander (both with compression ratio 10.8:1) and it requires 87 octane.
2004 RX330 owners manual on octane rating:
Select Octane Rating 87 (Research Octane Number 91) or higher. For improved vehicle performance, the use of premium unleaded gasoline with an Octane Rating of 91 (Research Octane Number 96) or higher is recommended.
There is a big difference between 'required' and 'recommended'.
Finally, the 3.3L V6 is the same engine used in the Highlander (both with compression ratio 10.8:1) and it requires 87 octane.
Last edited by cdnewton; 05-11-19 at 09:19 AM.
05-11-19, 09:13 AM
#641
Premium gas gives you more miles per gallon than regular gas.
Sorry, that's pretty much booo-gus.
Here's why.
Each gallon of gas that we pump from our local Quickie Mart is actually made up from as many as seven different ingredients. The exact amount of energy in each gallon of premium or regular gas will vary from company to company, depending upon what kind of additives they use.
In actual fact, you'll get a greater range of fuel economy between different brands of regular gas, than you will between the same manufacturer's regular and premium gasses. Interesting, eh? We thought so.
Finally, here's a nice irony: to increase gas' octane rating, companies add ethanol, when they're mixing up a batch of premium fuel. Interestingly, ethanol actually contains less energy than untreated gas, so the net result from the ethanol component is a reduction in your MPG. Other premium additives, however, have the reverse effect, and slightly increase your MPG. So okay, overall premium provides a very slight net increase in MPG, but it's so slight that we swear you won't notice the difference.
I always used the increased MPG that resulted from using premium as a justification to purchase it.
Too bad. Consider yourself better informed now, and stop lining the pockets of oil companies, okay?
https://www.cartalk.com/content/prem...egular-0#myth1
Sorry, that's pretty much booo-gus.
Here's why.
Each gallon of gas that we pump from our local Quickie Mart is actually made up from as many as seven different ingredients. The exact amount of energy in each gallon of premium or regular gas will vary from company to company, depending upon what kind of additives they use.
In actual fact, you'll get a greater range of fuel economy between different brands of regular gas, than you will between the same manufacturer's regular and premium gasses. Interesting, eh? We thought so.
Finally, here's a nice irony: to increase gas' octane rating, companies add ethanol, when they're mixing up a batch of premium fuel. Interestingly, ethanol actually contains less energy than untreated gas, so the net result from the ethanol component is a reduction in your MPG. Other premium additives, however, have the reverse effect, and slightly increase your MPG. So okay, overall premium provides a very slight net increase in MPG, but it's so slight that we swear you won't notice the difference.
I always used the increased MPG that resulted from using premium as a justification to purchase it.
Too bad. Consider yourself better informed now, and stop lining the pockets of oil companies, okay?
https://www.cartalk.com/content/prem...egular-0#myth1
05-11-19, 07:12 PM
#642
Premium
Both my RX and my wife’s Infiniti call for premium so that’s what I use. It helps that neither is driven a lot of miles. (6000 and 3000 a year) Usually get 30-50 cents a gallon off using gas card, so fill them both up once a month.
05-23-19, 10:11 AM
#643
I've never run anything in my RXs (300 and 350) - for more than a decade - but 87 and have never heard any knock/ping. I had O2 sensor issues with my 300 but my mechanic never asked me about the gas octane level I used.
Why spend money on 91 octane if you don't need to?
There are a lot of items in the manual that the manufacturer (especially the legal department) includes to protect their backside. I'm sure every ClubLexus forum user puts on their parking brake every time they turn off their car...
The best advice I learned a long time ago was never fill your tank up while a tanker truck is servicing the station. Since the fuel going in the station's tanks is churning up sediment/crap on the bottom of the station's tanks that have been there for many years - decades in some cases, just drive to the next station or come back the next day.
Why spend money on 91 octane if you don't need to?
There are a lot of items in the manual that the manufacturer (especially the legal department) includes to protect their backside. I'm sure every ClubLexus forum user puts on their parking brake every time they turn off their car...
The best advice I learned a long time ago was never fill your tank up while a tanker truck is servicing the station. Since the fuel going in the station's tanks is churning up sediment/crap on the bottom of the station's tanks that have been there for many years - decades in some cases, just drive to the next station or come back the next day.
10-09-19, 05:34 AM
#645
Driver School Candidate
How important to run 91 oct?
What does it hurt if you run 87 octane? The computer takes the timeing out when it regonze detonation so I what are you hurting by runing 87 octane?