cdnewton

I completely agree. To me the official statement from Lexus is the owner's manual and even it is a bit vague. What exactly is "for improved vehicle performance"? Does that mean my wife can break the land speed record driving between Wal-Mart and our house or that I will do some type of damage to the vehicle by not running 91?

We owned an ES300 that racked up just over 175K, but we needed AWD so we traded it for the RX330. The RX has 145K and we have always used 87 octane fuel. If I am damaging the catalytic converter by running the minimum octane called for in the owner's manual, then that is a different story.

lexus114

You never know until you try right? I am surprised to hear that you didnt notice any performance difference, I did.

lexus114

well, when ever you retard the timing on an engine (which is one of the things the ecm will do to prevent detonation) the exhaust temps are higher, and combustion temps as well. very hard on the cat. converters,and you simply dont get the power out put the motor was designed to give. Imagine you were back in the 60`s-70`s, would you have retard your timing,and altered carb. (from factory specs) just so you could use a lower octane fuel? Not me. Thats what your doing by using the lower octane gas. Yes it CAN run on 87, but not like it should. I have mentioned this already on here somewhere when I did an experiment on fuel grades. It ran out of steam on the highway after 70mph, rotten egg smell all the time,(esp pulling hills), ran okay around town,but it just didnt run as smoothly as it does on Premium. Lexus just covered their *** by saying you can use 87 octane, (for the cheapskates out there) And probably felt it looked better to customers than saying premium required. Hence the statement; for improved vehicle performance....yada,yada. So they are giving you the option, but what there really saying is use the Premium!

cdnewton

So let me get this right.

For the RX330, Lexus "...covered their *** by saying I can run 87, but they are really saying I should run premium .... it just looked better to customers than saying premium is required."

On the flip side, for the RX350, Lexus specifically requires premium. The RX350 manual further states "If this premium fuel is not available, you MAY use unleaded gasoline with an Octane Rating of 87. The use of such gasoline will cause persistent heavy knocking. If severe, this will lead to engine damage."

If Lexus is really saying they want me to use premium, why wouldn't they take the same approach for the RX330 as they do with the RX350 and state that fact in the owner's manual?

lexus114

I really dont think you understand what I said ^^^. Hey, if you like using regular fuel,and having less mpg`s as well as lower performance from your vehicle, and higher emissions due to not burning as clean, then be my guest! If you wanted to use regular fuel with no consequences like mentioned, then you should have bought a Ford my friend.

"If Lexus is really saying they want me to use premium, why wouldn't they take the same approach for the RX330 as they do with the RX350 and state that fact in the owner's manual?" Why do you think it states; "for improved vehicle performance,the use of 91 octane or higher is RECOMENDED?" Do you know the meaning of the word recommended? 1) to entrust, 2) to suggest favorably as suited for some position, 3) to make acceptable, 4) to advise? That is stated from my Websters New World Dictionary btw.

cdnewton

As far as me not understanding, I quoted what you said. I am looking for specific facts and discussions for this debate.

You have a "roll eyes icon", make a statement about "cheapskates", etc. and you imply above I will have higher emissions, less mpg/performance from 87. I run premium in the Audi because the manual specifically calls for it. The Audi (and RX350) have a "premium fuel" label on the dash and near the filler neck; the RX330 does not make that same statement. All I can get is the "for improved performance" statement in the manual.

The car passes Colorado emissions with flying colors -- they always stop the test early because the emissions are so clean. Also, when I ran premium on 3 back-to-back tanks, we were still getting about the same mpg from our RX (it was a fraction better with premium). My butt-dyno could not feel the difference that the extra 5-10hp from premium provided nor for our situation was it enough to justify the cost of the extra $.20 per gallon.

So, for this discussion, I will take the opposite approach. For those that want to run premium in the RX330, go ahead, but based upon our vehicle and usage, you would be wasting money at every fill up.

We plan to take our RX to at least 250,000 miles, if we have engine damage or catalytic converter damage as this thread implies, I will come back to post that fact and let everyone know. YMMV.

lexus114

what ever man. I have explained to the best of my ability on this subject. The ONLY reason you may get away with using reg. fuel is your altitude.

jfelbab

An observation:

As gas prices increase premium is an even better deal. With gas at $3 a gallon premium (20¢) is a 7% increase in cost. With gas at $5 a gallon premium (20¢) is only a 4% increase in cost.

As I've posted previously in another thread, I've made now twenty-one 1,500 mile road trips on the same roads and have proven to myself that I get 2 MPG more when I burn premium. This is at a cruise controlled, 75 mph, tank after tank on clear freeways.

I'd also point out that in my RX330 I get a noticeable loss of power when I burn regular and this is obvious in the increased downshifts when encountering hills. I also get rotten egg smell on these hills when using regular. That indicates incomplete combustion and would definitely contribute to an early cat failure.

The point I'd make is in my RX330 AWD, with my driving conditions, it is more economical for me to burn premium. There are way too many variables (altitude, terrain, driving style, vehicle tolerances, regional fuel additives, fuel brands etc.) to say this would hold true for everyone but in my case, I don't save any money by burning regular. It actually costs me more per mile to burn regular.

lexus114

Thank you sir!

quantfutur

One of my colleagues has a Mercedes station wagon and a BMW suv, and despite the fact that premium is recommended for both vehicles, he said he 'researched' it and decided he could run them on 87 - and so he does.

Because my RX330 has run 6 years on premium, I wonder if that isn't a contributing factor as to why I got the bad carbon smell as soon as I switched to 87; e.g., too late to re-train. Nonetheless, my cat did go bad in the RX300 (and that car got every service on time)... and I don't want to see that happen with my RX330. So I'm sticking with 91.

Lexus114 -As the cost of premium is now $4.19 here, I am keeping to 60mph and legal limit in town, so perhaps if I had been cruising I would have experienced lesser performance on the 87. But the carbon smell was a clear enough signal that things were not right!!

lexus114

I know, gas prices are getting...no are ridiculouis! but the few cents you save by putting in regular do not make up the 2mpg less in millage alone. As far as being too late to train it to use 87, really all you need to do is reset the ecm on or about the second or third tank. Then it starts out on a fresh slate. Thats how I did the experiment using regular. The woman that owned mine from brand new was most definitely using 87 gas. When I first bought it @ 59k the tail pipe had a black carbon looking substance in it,and it didnt run as good as it does now. It took more than a year for this thing to finally feel like it`s running like it should. Sound crazy? maybe. But I have used nothing but 92-93 except for that very short stint with around 4 tanks of 87. And when I start it up in the morning, the exhaust actually has a clean smell to it.

groomerz

If you run 87 for many tanks then go back to premium and expect performance but there is no change. It is because the knock sensos have retarded the ignition timing of the ECM to accept 87 octane and the ECM has learned the retarded timing as a its new basepoint. Fill up with premium and reset ecm by disconnecting battery for 5 min. The ECm will go back to factory ign bassepoint settings and performance/mileage change should be noticeable then.

lexus114

Although it`s best to clear the ecm via a scanner, you are absolutely correct.

cdnewton

Overall, that was a good discussion/debate.

quantfutur

Agreed; I appreciate the information received.