AhBei

On my 2015 RX 350 base model with sport appearance package, I’m looking to add on a OEM transmission cooler. I am assuming the coolers are all the same across all models, which differences are the air dam. Would I need one for F sport? Is F sport bumper same as sport appearance package bumper? If anyone done so, or has stock cooler hoses routing?

Clutchless

This is a robust trans if you just change the fluid at 50,000 etc. No real need for an extra cooler unless towing.

The OEM trans cooler is integrated into the radiator. I have no idea of the cost but check www.myLpart.com or www.lexuspartsnow.com

It may be far easier and cheaper to add an aftermarket trans cooler such as a B&M Super Cooler. https://www.summitracing.com/search/...er-oil-coolers

I have installed 2 of these, first in my 1995 Explorer and then in my 1994 Mazda MX-6, They use zip ties to attach to the front of the radiator area. Then run hoses to the transmission. It also adds a bit more capacity. The appeared to work great as I drove both for well over 100,000 miles with no trans issues and both were known for problematic transmissions. I also did regular fluid flushes or exchanges with Mobil 1 synthetic ATF.

You would have to find the cooler line connections from the transmission, get some connectors and hose then run everything to the front of the radiator.