Originally Posted by Bocatrip

I'd be extremely careful when it comes to your next move. You already mentioned that the car shifts smoothly and you mentioined you think the fluid looks dark and possibly smells burnt. Before doing another thing.. you have one major thing in your favor. Your car shifts as it should. Go to a shop you trust (not necessarily Lexus) and ask them to inspect your fluid. If you had mentioned your car is not shifting correctly.. that is another story and you would have no choice to to change the fluid. Here you have a high mileage car that by changing the fluid and by changing all of the fluid, you might very well end up with a car that won't shift or even move! The varnish that has built up over time might be the only thing holding your transmission's clutches from slipping. Changing transmission fluid (unless you are the original owner) might be a throw of the dice... be careful my friend. Do yourself a favor and reread the post from Johnhav430. It might be very relevant. You want to do the right thing, but it might not necessarily go that way. If it were me? I'd leave well enough alone until I had a problem which you might not ever have. Good luck and let us know how it works out.

Originally Posted by Stu

this is 100% true. I know because I did it to a perfect and perfectly running low milage Audi and lost the transmission 10 days later.