FWIW, due to the high gas price and my new 90-mile round-trip commute, I decided to downgrade to 85 octane - regular in Colorado.

To my surprise, there's no decrease in performance or gas mileage. No pinging or knocking. I'll keep monitoring this and keep y'all posted.

I used 85 once when I moved to Colorado two years ago. I noticed decrease in acceleration and gas mileage back then. Not this time, perhaps the ECU has gotten used to the thin air here.

 

I have always used 85. Never a problem for 30000 miles. I get from 23 to 25 MPG's hwy.
Best Regards..........Bob

 

I do notice about one MPG drop (from 24.5 to 23.5 according to the computer.) It may be attributed to the 5-day 100+ degree temperature in Colorado. My A/C was on full blast the entire commute.

No noticeable performance loss. However, my tranny seems to shift smoother than before??? That's a surprise. I'll keep an eye on it.

 

Wow, you guys have great fuel economy, my wife's RX only got about 17-19 on the highway. Wonder if there's something wrong with her truck, and i just changed the air filter too

 

It helps that you're in higher elevation. I always get better mileage in the higher elevations w/lower octanes.

 

In Mexico City, higher than Colorado by about 2,000 feet, the lower octane is garbage. That is because Pemex Magna (87 Octane) is loaded with sulfur. The octane boosters (I have experimented with many) do nothing for the Pemex Premium (92 Octane). The Magna has a higher sulfur content outside of Mexico City.

However, friends with OBDI and mechanically-based cars do show improved performance from using octane boosters.

If I ever get out to Colorado, will be sure to try that experiment with my rental car.

 

I used to get about 17 mpg in New York City, about 21 mpg on Long Island Expressway. The light traffic and thin air in Colorado may have helped. I routinely get 24-25 mpg on the highway. My commute is 90% highway with no rush hour traffic.

It was cool the last 2 days, so my mpg is back up to 25.3. No performance loss, and like I said, the tranny actually feels smooth now. (dunno why) I'm using 85 from now on.

 

If I drive normally, I have found that I get between 14 and 15 mpg here. In the states, this goes up above 20 (I think 21-22 when I was in Texas).

If I floor it everywhere I go, you can be sure that MPG drops to 10 to 11.

 

guys, i'll think i'll try to slowly switch back to 87 and see if it improve.

 

Funny, I just switched to Mid grade gas and noticed a world of differance as far as smoothness goes! 330RX

Im sticking with Mid grade

 

I think the RX330 actually recommends premium gas, though regular will work. So mid-grade will definitely work better than regular in your RX330.

My RX300 recommends regular gas, though premium may improve performance according to the owner's manual. It can go up a long 3-mile 7% grade in top gear at 70 mph, so what more can I ask.

 

I have an '04 RX330. The manual says 87 octane or above. Does not rec. premium specifically.

 

BUT it does say you may see better performance with Premium! Which Is what Im noticing just jumping up to 89 VS 87

 

Good for you. I drive in some hilly terrains in thin air, so I can detect any slight change in performance. In my case, there isn't any difference (85 vs. 87) that I can notice. I do acknowledge the fact that my RX300's manual says higher octane give better performance.