There's a whole bleeding procedure the techs must follow on their Lexus provided laptops. I wouldn't worry, timing belt service is much more complicated.

Do you actually believe that there can be a lubricating fluid that is "lifetime"?

 

i have no idea, but until someone else backs their $$$$$ behind the recommendation, i can't really go and question what toyota engineers type into every GX owners manual. right?

 

Most American cars last 100k miles (eventhough the GX is Japanese), maybe that's what "lifetime" means, every 100k intervals. Just to be safe I would change it every 100K.

 

I've been through this with my other vehicles. Usually a "lifetime" is defined as 100k miles by the manufacturer, after which they expect you to buy a new(er) vehicle. It's been shown in lab testing that "lifetime" ATF does and will break down. The most significant problem with changing your (automatic) fluid is that it very well may dislodge particles that have come to settle in the fluid over time. Once disturbed, these particles can clog passageways and syncros in the transmission which can actually lead to transmission failure and replacement.

 

Very easy task:
Catch all of the old fluid and refill with the exact same volume as was drained (as long as level was correct and tranny had no leaks).
My GX has 259K miles, shifting very nice and smooth, fluid was replaced so far only ones at 123K miles.
Very true:
Do the fluid replacement on regular 60K basis, other wise new fluid will wash all the settlements and inner surface coating down clogging up new filter or even worse by entering the valve body.
Neighbor across the street did his first fluid change on RX300 at 140K miles before round trip to Florida, new filter clogged up at 700 miles into their 2.5K miles trip.
Draining the synthetic fluid, washing out filter (since they had no exact replacement) and filling tranny with regular less detergent agressive fluid let them finish their one way trip.
In Florida, they got new filter and oem fluid but CEL and solenoid code showed up. Shifting was fine, so they made it back home and had the fluid and filter replaced ones again. Solenoid code with check engine light is on and off since (now for about 20K miles).
I believe Mercedes is using fluid replacement procedure by disconnecting tranny cooler return line, starting up the car and catching the old fluid being pumped out while pooring in new stuff.
When you see new clean fluid comming out of the line, stop the flow by turning off the engine.
Then reconnect the line, drain just the pan, replace filter, reattach pan with new gasket and refill to correct level.

 

I can appreciate wanting a starting point. You don't know if someone previously had a lead foot, towed, hard on everyting, even though there is service verification. Changing fluids because you want to, to get a base line or starting point, can't be a bad thing. If it makes things right in your head, spend the money.

 

Yup, first thing I do before I start messing with anything else on a newly acquired used car purchase is to change all fluids. INCLUDING: Brake fluid. Brake fluid is very hygroscopic, meaning it absorbs moisture from the air. Even though it may look crystal clear, it can still contain moisture. Why in the world would you not flush your brake system every 15K? I mean a couple litres of fluid, a buddy with some in shape thighs or a pneumatic hydraulic system pressurizer and a couple of hours gets the job done.

Now, the tranny fluid is a little more touchy an area. Lifetime fluid must be referring to the lifetime of the tranny as far as the manufacturer is concerned. My only other auto tranny car was a Volvo 855 t5r with a bit more boost than factory, I considered this extreme operating conditions for the tranny so I flushed and filled every 60K. These boxes were notorious for failure at around 85K. I am not towing much with my current GX so I am going to wait until it hits 100K to do the Wynn flush and fill.