Could somebody tell me if at all anybody used non standard ( Mobil/Penzoil) ATF fluids has been ever used on GX model from Non dealers
if so your suggestion the brand, I had gone to the dealer and he suggest All toyota & lexus engines
should mandatory used the Transmission Fluid Type IV sold by the dealers in order for the transmission
warranty, Is it true, your advise !!!!

If your GX does not have a tranny dipstick then it is a "WS" ATF which leaves you with the safe choice of using original Toyota WS ATF only.

The 2003s uses the old T-IV which some aftermarket ATFs are compatible. I personally have Amsoil ATF in my 2003 (with tranny dipstick), I believe Valvoline Maxlife ATF is T-IV compatible too.

I have 30,000 miles on Royal Purple Multi Spec. Automatic Transmission Fluid without any problems. I am about to do a fluid change again. Please note you need a scan tool to read ATF temperature for correct fluid level check. I can send you the manual you could follow if you need it. I use their products for every fluid my vechicle requires.

I order it from here. Stock up on all fluids at once since they charge $9.00 fee on all orders.

http://www.jegs.com/i/Royal+Purple/831/01320/10002/-1

You can call Royal Purple technical support at phone: 281-354-8600 with any questions.

Hi could you email a soft copy of the manual to my email address. mann68'2gmail.com... appreicate your support.
thks - mann