Boyd Posted October 3, 2006 Share Posted October 3, 2006 24mpg!?!?!?! If that's what using premium gets me, I won't say another word. I average 18mpg. Using your calculations and $.30/gal increase for premium, I'm looking at $250 extra over the course of a year. And for what? To think I'm doing myself a favor? Unless someone can show me proof of either an considerable increase in performance, or mileage, then I'm doing myself a bigger favor by putting that $250 in my pocket. Running 87 will not harm your engine in any way. So don't think that using 93 is going to make it last longer. That being said, I'm filling up with 93 tomorrow to start my first test. And keep in mind that this test will be taking place under ideal weather conditions...Little to no need for AC and no need to idle the truck to warm it up in the morning. We'll see, but I'm not expecting much. And lastly, the manufacturers recommended fuel is 87! Well, maybe times have changed. My 2006 RX330 manual states clearly "Premium unleaded, octane 91 (research number 96)". It goes on to say, if that is not available, you may use 87 (research 91). Also, when I open the fuel door it states unleaded premium fuel only. Oh well, Boyd Quote Link to comment Share on other sites More sharing options...
bciesq Posted October 4, 2006 Share Posted October 4, 2006 Well, maybe times have changed. My 2006 RX330 manual states clearly "Premium unleaded, octane 91 (research number 96)". It goes on to say, if that is not available, you may use 87 (research 91). Also, when I open the fuel door it states unleaded premium fuel only.Oh well, Boyd If you get a chance, could you please type in the whole paragraph re: octane? I'd like to compare it to the 2005 version that I quoted above. Thanks, Ben Quote Link to comment Share on other sites More sharing options...
ggloversr Posted October 5, 2006 Share Posted October 5, 2006 Hello all, I just had noted that Octane 87 help the transmission shift smoothly. I have a problem with the lag time in low speed; the transmission seems to slip into about 2 second of Neutral. This just happen when I put Octane 89 or Premium 93. It sound like did make any sense that the cheap gas run smoothly than good gas. Is there any body has the same situation? I have an appointment with dealer for checking ECM CALIBRATION SHIFTING ENHANCEMENT. I would like to have you recommend in this case. Thanks a lot in advance. Hi, I'm having a similar problem. I found that mine shifted better at first when I used better gas, and now after about 2 months of it the transmission won't shift into 4th gear or sometimes even go down to 1st gear at a stop. LEXUS we have a PROBLEM!!!! Quote Link to comment Share on other sites More sharing options...
Boyd Posted October 6, 2006 Share Posted October 6, 2006 Well, maybe times have changed. My 2006 RX330 manual states clearly "Premium unleaded, octane 91 (research number 96)". It goes on to say, if that is not available, you may use 87 (research 91). Also, when I open the fuel door it states unleaded premium fuel only.Oh well, Boyd If you get a chance, could you please type in the whole paragraph re: octane? I'd like to compare it to the 2005 version that I quoted above. Thanks, Ben OK Ben, Here ya go, right from the manual. "GAS STATION INFORMATION _ Fuel selection: Premium unleaded gasoline with an Octane Rating of 91 (Research Octane Number 96) or higher required for optimum engine performance. However, if such premium type cannot be obtained, you may use unleaded gasoline with an Octane Rating as low as 87 (Research Octane Number 91)." The key phrase there is "for optimum engine performance". But, "if such premium type cannot be obtained". So, they are heavily suggesting premium. Quote Link to comment Share on other sites More sharing options...
bciesq Posted October 6, 2006 Share Posted October 6, 2006 OK Ben, Here ya go, right from the manual. "GAS STATION INFORMATION _ Fuel selection: Premium unleaded gasoline with an Octane Rating of 91 (Research Octane Number 96) or higher required for optimum engine performance. However, if such premium type cannot be obtained, you may use unleaded gasoline with an Octane Rating as low as 87 (Research Octane Number 91)." The key phrase there is "for optimum engine performance". But, "if such premium type cannot be obtained". So, they are heavily suggesting premium. Thanks. Looks like they changed the wording from 05 to 06. I wonder if they changed the fuel mapping as well? Quote Link to comment Share on other sites More sharing options...
Topshelf Posted October 6, 2006 Share Posted October 6, 2006 That's also quite a bit different than the wording from my '02. And just an update so far....No noticeable performance increase, and an average of 15.2mpg.:D I've done 100% annoying city driving so far though. Hopefully I can get it out on the highway at some point. Otherwise I might need to run 1 more tank of the expensive stuff before I can end this test. Hmm, I imagine that's really when I'll notice if there was a performance increase though.;) Quote Link to comment Share on other sites More sharing options...
jgr7 Posted October 7, 2006 Share Posted October 7, 2006 If you don't reset the computer it will take several tank fulls for the computer to account for the different octane of fuel you are using. It has to monitor all the sensors that give it information on every aspect of the fuel burn and then start to adjust to meet the needs of the car. The computer has no clue what octane of fuel you put in the tank it only gathers data from the sensors and applies a programed algorithm to the various components that make the engine run like the engineers programed it to. Be patient and gather data then report in, the main thing is you have to drive exactly the same for the test to be accurate. Quote Link to comment Share on other sites More sharing options...
gotdilbert Posted October 7, 2006 Share Posted October 7, 2006 Yeah, I just recently switched to premium and I noticed the unsmooth shifting even more than before. Quote Link to comment Share on other sites More sharing options...
huylanalexus Posted October 24, 2006 Author Share Posted October 24, 2006 After so many test with running many of different gas. My RX only drink Premium 93 for better performance, no Pinging noise. Quote Link to comment Share on other sites More sharing options...
Topshelf Posted October 27, 2006 Share Posted October 27, 2006 Been meaning to update this. After 500+ miles of driving with 93 octane, my gas mileage dropped to a constant 16mpg with no perceptible improvement in performance. I've switched back to 87 octane, and am already back into the 18mpg area with no perceptible loss in performance. So after all this, I'll stick with my original thoughts. Until someone can show me dyno charts of 87 & 93 octane, run under the same conditions, with a true increase in performance for 93, I'll happily use the recommended 87 in my RX300 while both saving money and getting the same performance. That was one very long sentence. lol Quote Link to comment Share on other sites More sharing options...
tmastres Posted October 27, 2006 Share Posted October 27, 2006 Been meaning to update this. After 500+ miles of driving with 93 octane, my gas mileage dropped to a constant 16mpg with no perceptible improvement in performance. I've switched back to 87 octane, and am already back into the 18mpg area with no perceptible loss in performance. So after all this, I'll stick with my original thoughts. Until someone can show me dyno charts of 87 & 93 octane, run under the same conditions, with a true increase in performance for 93, I'll happily use the recommended 87 in my RX300 while both saving money and getting the same performance. That was one very long sentence. lol Funny enough, after doing a little bit of research I found out that the RX's V6 is high enough compression to take advantage of premium fuels. Seems to me though that the only way to see that extra power is get it inot to its power band up in the 3500-4000 rpm range which is almost impossible to do with the auto tranny. And of course this would certainly lessen you mileage. Guess my conclusion is that there reallyis no difference in day-to-day driving. I switched to 87 from 89 about a year ago and have noticed no difference at all. By the By if anyones lexus is pinging with any fuel grade , I'd say you've got a problem other than the fuel. Quote Link to comment Share on other sites More sharing options...
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