simpson

My 2010 RX that is AWD and has the tow package option with the heavy duty trans cooler has started to leak. It's slowly seeping out of the lower line. I do all the maintenance on my vehicle myself and have been looking into fixing this. It is leaking enough to occasionally leave a few drops on the ground.

I believe what causes this is the rubber line slides onto a plastic fitting which is part of the trans cooler. This fitting seems to easily chip. Although it's plastic, it's almost like it has a really thick coat of paint on it and when this finish flakes off, it makes the surface rough which I think makes the hose hard to seal.

I haven't done anything yet because I don't know the proper procedure to refill the transmission. It doesn't have a dipstick and I see everyone refers to checking the level by the temp of the fluid. I would like to know what the proper procedure is to refill the transmission. Can't find a service manual for this car either. Any help would be appreciated.

RX in NC

There are several threads here that explain how to refresh your ATF. Because only approximately 2.25 quarts of ATF will drain out of the pan each time, most of us do three successive cold drain-and-fills. Type "RX350 ATF drain-and-fill procedure" into your search bar and read the threads carefully. If you have the necessary tools, it is a relatively simple job. The key is to accurately measure the fluid you drain out and add the same amount of fresh fluid each time.

Clutchless

If you follow the above instructions you can handle this project.
If it was my RX I would carefully collect the fluid that drains when you pull off the trans cooler hose and measure the amount. Then open the drain (after making sure you can open the fill bolt) and separetely measure that amount of fluid. Note that there is a plastic overflow tube inside the drain hole that must be removed to completely drain the pan. Both take a 6mm Allen wrench.
In a typical cold drain and fill you drain about 2.25 quarts as mentioned above. Add that amount to the amount you drained from the cooler line and that is how much you need to put back into the transmission. Maybe add 6 ounces more for spillage etc.

This is the giant transmission fluid thread mentioned above: https://www.clublexus.com/forums/rx-...d-threads.html

This thread discusses a complete fluid exchange but it has some good photos of the trans cooler lines.
https://www.clublexus.com/forums/rx-...oler-100k.html

This discusses drain and fill.