foreste1

Looking over all my service history and up until 190k everything was done at Lexus, and I dont see in any records where they changed transmission fluid, only checked level. I now have 255k and wondering if I should drain and fill or leave alone, transmission works perfect so dont want to mess it up.

Lexus4321

It needs a new filter. I would drain it, drop the pan, install new filter & pan gasket, re-fill with Toyota trans fluid.
Refill with exact same amount that comes out.

dblshock

...or do a series of 3qt. spill/fills...keep an eye on fluid color, til the fluid is obviously red.

foreste1

Whats interesting is its been serviced at Lexus all the way until 190k and I cant see where they ever changed fluid, just inspected?

chiph9

Lexus sold it as "sealed for life". Now that they commonly have 200k+ miles on them, that's not so true any more.

I have been doing a drain + fill (NOT a flush!) every 30k miles at the same time as the 4x4 service, and that swaps out somewhere around 1/4 to 1/3 of the fluid. I did have the filter changed at 150k miles (given the poor maintenance done by the previous owner..), and the mechanic said it was perfect - no sparkly bits. So getting that done is up to you. If you tow or spend a lot of time offroading you might need to shorten that interval. If you ford rivers, get all the lubricating fluids changed because the vent hoses might have gotten submerged.

Chip H.

Lexus4321

If never done before, the filter is more important. I believe this "world trans" is way beefier than what the engine can supply, so it's (trans) probably ez on beating up the trans fluid. It's usually trans oil temp that hurts things, not so much shifting and torque inside the unit.