Ok,So I was having a brief discussion with another member here the other day. It was re; getting 16-17mpg right now on premium fuel. So I decided to try the 89 octane for a tank and a half,and so far I`m getting 17-18mpg! And the power is about the same?? I do remember trying this in my 2001 RX,but they had overactive knock sensor`s in those,they have since been improved. I will continue with my little experiment for a while and see how it goes.

 

I don't know about your weather lately in Bethlehem PA but it is warming up here in WI and my mileage on my car has gone up about 1 MPG. This may be why you are seeing the 1 MPG with regular. I'm more convinced now that it doesn't make a difference if you use premium or not. This engine isn't high compression so I guess it makes sense. Thanks for testing this.

 

I use 87 regular here on my 2005 rx330. occasionally I will use 89 but its only like once every 2 months and i don't notice a difference. I get 23-25mpg average though 75% of my miles are highway miles.

 

Well,figure this one out guy`s. I have used two tanks of 89 octane fuel.So far the millage is better than on Premium. Power is down (some) on the highway but thats all.Then I used two tanks of Premium fuel,yes the performance was better on the highway but I actually lost .5-.8 mpg`s? Now I`m back to the 89 octane fuel,and millage is up again.The real test will be when it gets hot out and the A/C is on etc. It might be doing well now because it doesnt have to pull much timing. We will see......

 

Have never used anything but 93 octane on our '09. We can get it in our area for 10 cents more then regular on Mondays. For the little difference in cost I stick with factory recs.

 

This is also the time of year where gas station are changing the blends in the fuel from winter blend to summer blend which would affect mileage a little

 

Thats not for another month at least. When it gets hot outside will be the test. Hey,if I`m going to have the same or better millage on mid grade fuel but slightly less power. I think I can live with that.

 

Here is WI they are already using the excuse about winter to summer blend to increase prices 10 to 15 cents.

 

just an up-date,Still running very well on the mid grade.

 

I use 87. I use a Fuel cleaner every 4,000 miles. So far average about 20 MPG combined. No noises.

 

Thats good to hear. But you have the black soot like stuff in the tailpipe using 87 dont you? And when you push it hard,does it smell like rotton eggs? If yes to any of these questions,try using the 89 for two tank fulls. Then reset the ecm. I bet you will like the results. You will have a cleaner burning engine,especially in your hotter climate down their.

 

I would use 89. Buy I purchase my gas at the local Costco and they only offer 87 or 93. And no I do not have the rotten egg smell and no excessive black soot on my tail pipe (because I clean it all the time, LOL!). I am perfectly happy with 87, quality 87 Octane at Costco.

 

Did you get your stoplight (LED) fixed yet?

 

At the moment it stopped flickering. Get this one,I found one on e-bay (a r/r lens w bulbs and all) for a buy it now price of 49.99. As soon as I asked the guy if that included the led bulb for that price,he raised it to 99.99! Even though that was still a steal,I backed out just for the principle.That really pissed me off.

 

I bought my RX brand new and ever since I drove it out from the lot I always put 91 octane. My mechanic friend told me that lexus recommend the premium gas to protect the catalytic converter and the extra miles you get with the premium gas is a bonus. To replace the converter for this Rx I believe is around a thousand bucks.