I have just purchased certified pre-owned 2003 GX470(51,000mi).
It seems to be in a good condition so far except "Clunk". I have brought it to the
dealership but I have to wait for a few weeks since the updated drive shaft isn't
available in stock. Anyway I believe that this new drive shaft will solve the clunk
problem.

Meanwhile, I would like to know if regular gas(87) is good for this vehicle or not.
Sales person of the dealership said that I should put premium gas for better gas
mileage but I doubt it. Please kindly let me know what risk or problem I might
have if I use regular(87) gas instead of premium(91 or 93).

Thank you for your advice.

i would not recommend 87, i put in premium, if u put in 87, you will for sure notice a difference in performance. im not sure on this part though, but it might not be to good for then engine either. hope this helps

What does your manual say? My RX it is fine to use 87.

Thank you for your comment!
The manual says:-

"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(Reserch Octane Number 96)
or higher is recommended."

Could someone tell me what "Research Octane Number" is?
There are possible selection of 87, 91 or 93 here in GA. Can I then
use Regular(87), or Super(91)?

Well if the manual says to use 87 or higher...then I would use 87...That is the same thing that the RX says and it is just fine to use regular (87) in it. I don't think you will notice much between 87 and 91 in a GX or even a RX...and I am sure if it would harm the engine they would not tell you that you could use it.

By the way not sure if you tried to search but there are quite a few gas topics at least for the RX anyway...

good luck! Post a PIC of your GX...my boss has a 06...nice!

Thank you so much for your advice! Yes. I will use 87 and will see if there should not be any problem with this type. I will post my GX470 soon.

Have to say I'm no expert. I have a '05 with 13K. I'm not an aggressive driver. I've used both 87 and 91. Alternating about 3-4 weeks. Maybe I notice better acceleration with 91 but I don't notice any significant difference in milage. If anything, less with 91. Could that really be? If so, is better performance at the expense of less milage? I now consistently use 87 (Sam's) and average 17.5 m/g (that's the actuall average not what is recorded on the car computer which I find is consistenly 1.5 m/g higher.). That's mixed 50/50 city/highway.

Thank you for your comment about your experience of gas mileage!
Yes. I am not an expert too, but I learnt the gas mileage is rather
depending on how you drive. What kind of performance can I expect
if I spent more and put 91 or even 93....? Accelearation is getting smoother?
Anyway, I thank you all guys' kind advice which is very helpful indeed.

It really depends on the engine. I think the new VVT-i engines require premium, but try 87 and see if you notice any engine pings. If you do, then go to 91 or higher.

I have 04 GX and have been using 87 since the day I'd bought it - never noticed any "pings" in the engine and am very pleased with acceleration. Would not go any higher unless otherwise specified in the manual.

Only the 05s and newer have the VVT-i engine which MAY require premium. I know my 4Runner doesn't require premium but had a little engine ping ONCE so far in it's 3,000 miles it's been with me. I still continued using 87 and it never came back. It was very strange.

I have to apologize that I made a mistake. Here in GA
gasoline types are 87, 89 and 93.

Anyway, I will continue with 87 to see if there's a problem
coming up....

Meanwhile, I thought VVT-i engine is also in my 2003.....

On the 06, the gas cap saids 91 octance require, on the 05, the manual saids 91 octane recommanded. They both have the same engine, dont know why Lexus change the premium fuel requirement. 03 and 04, the engine is different, the compression ratio is lower, so you can difinitely use 87 octane.

I also have try both 87 and 93 for a few tank at a time. The 93 does make a difference performance wise. Barely noticable during everyday driving and at low rpm, but difinitely noticable at higher rpms. Gas mileage wise, on the computer, it show about a 0.5 mpg difference.

The G Man, your kind and clear answer gives me a confidence to
continue using 87 for my 2003 GX470. Thank you very much indeed!!

[quote name='TM8000' date='Sep 18 2006, 06:18 PM' post='208433']
The G Man, your kind and clear answer gives me a confidence to
continue using 87 for my 2003 GX470. Thank you very much indeed!!
[/quote

I think 87 octane is just fine for daily (not performance) driving. I tow two horses and their trailer twice a week, and 91 octane gives me subjectively better performance. But, with 87 and 91 octane being separated by 26 cents per gallon in my town, I'll stick with the 87.

Hi. Reggie,
Thank you for your advice. I will definitely use 87 for my 2003 GX470
since my wife is primarily driving this vehicle with absolutely normal
ride almost at the legal speed.... By the way, dearler advised me that
I should not purchase a gas from discount station like Racetrac, Kroger etc...but I do not believe that the quality is so much different among
stations.

The quality is not so much different among stations, its the additives you have to worry about. I usually stick with the name brands, but its up to you.

some gasoline brands may put higher levels of detergent agents in their fuels that could help your injectors stay clean, but the gas itsellf is a commodity that is the same. I run a bottle of injector cleaner through mine every 6 months or so just to avoid any troubles.

I have an 04, without the VVT, and 87 octane gasoline works just fine for me. I tried 91 and 93 octane and noticed no difference whatsoever in milage or performance. Maybe if I was going to be towing a substantial trailer I'd go for the premium, but for my normal driving, it is not of benefit.

Thank you all for your comment. I understand from you that
the quality of gasoline is same wherever I purchase but additives
varies. I usually use QT as it offers good price.(one of the cheapest...)

I have an 03 GX470 and have tried all 3 levels of gas (87,89,91)

-87 actually made my vehicle sluggish at take off.

-89 felt right with take off and performance on the highway

-91 didn't make enought difference for me to continue to pay the big difference.

So, I decided to stick with 89 (mid-grade) and I have been very happy with the performance of my vehicle overall.

Good Luck and get that clunk taken care of ASAP....all the dealers should have the part in stock now....

Kim

Thank you so much for your comment, kimber33!
This is also a good reference and I will try to test 89 myself
to see the difference. Upcharge of $0.10/gallon isn't bad
if I can expect a better ride, is it?

Meanwhile, I am really concerned with the information
about a cancellation of TSB for "clunk". The dealer keep
telling me that updated driveshaft is very long back order
and they do not know how many more months I have to
wait for the clunk of my GX470 to be permanently fixed.

I checked with the other Lexus dealership around Atlanta
but they also said the same. They said that all I can do
is to just wait as long as my name has been on the waiting
list.

Not sure if you have actually went in to the dealer to complain about the vibration of the vehicle or not...if you haven't then you should...just actually make an appt to complaint about how bad the vibration is when you are stopping and they should put you fix it for you right away....Many people are on the waiting list to get the clunk fixed because they aren't having major problem...So make yours a major problem and you will go to the front of the list...not just a stand by.

Good Luck

Kim

Has anyone tried 93 octane in a GX470? It's not available direct from pump in California, but one can blend 100 octane racing fuel with 91 to get 93.

We have 93 and 91 here in MA, made no noticable diff. in my GX.

I used 93 octane fuel when I lived back east in my 07 GX and now use 91 octane fuel out here and I notice no difference whatsoever. As long as its labeled Premium Unleaded, there should be no difference in performance.

I use 87. When I use 91 or 93 there is little if any difference in performance and no improvement in gas mileage. Save you money.

Using a gasoline with a higher octane rating than your engine requires gives you no benefit at all...none. The only benefit is to the gas station you buy it from. NO GX would gain any benefit from using anything higher than 91 octane. Those of us with pre 2005 models don't really even gain anything from using higher than 87 octane.

ding ding!

I use premium fuel in mine. Premium is 93 octane here. I'll have to try 91 (Midgrade?) and see if there is any difference.

I use Premium. I get better gas mileage. 20-40 miles per tank.

I just picked up my 2008 GX470 about 230 miles ago

I was told by the dealer to put atleast 91 in for optimal performance. I have been using super 93 since 91 is difficult to find in the North East. Oil is at $109 a barrell.... SWEEEEEEEEEEET!

For VVTI engines, it is not recomended that you use 87 Octane for possible knocking. (05-up) For those that have Non-VVTI engines 87 is fine. (03-04). For any engine type, I would suggest using a gas additive just to keep valves clean.

What brand name additive are you using?

Toyota 4 runner V8 has the same VVTI engines and it recommands 87 octane.

Yes. the 4Runner has a VVTi V8 & V6 engine, but only requires 87 for both (G Man, it recommends 91)

The CLUNK is from trapped air in the driveshaft. When braking occurs the rear-end twists a bit extending the driveshaft. When you finally stop, the rear-end is cocked and ready to unload and force the driveshaft back together. When it finally overcomes the air trapped in the driveshaft it lets go with a pop! My 05 GX470 was dealer repaired including the new driveshaft as well as sturdier rear lower controlarms (to lessen the rear-end flex). No problems since. A local mechanic had his own fix for his wifes GX. He drilled a pinhole in the driveshaft to let the air escape thus fixxing his "clunk".