I have searched but cannot find the answer. Is there a coolant drain plug on the back of the engine on a 2014 RX 350? Any pics? If so, does the radiator drain and this drain all the coolant from the system so there is no flushing with water, diluting, etc?

 

There are engine block drain plugs but they are difficult to find and access and even more difficult to remove. The Toyota coolant is so good that all you need to do is drain the radiator and refill it with more Toyota Super Long Life premixed coolant. That will refresh enough of the coolant to protect your motor. There is no need to try and drain the block, do a flush etc etc.
Even the Car Care Nut on youtube, who is a Toyota Master Tech says that is all you need to do.

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That is counter to all other input that calls for a series of dilution cycles with distilled water.

 

There is all sort of information on the net. Understand the issue at best and then make your choice.

Service manual says that replace the coolant at 100K miles by draining from the engine block and radiator.

Extreme option would be drain, flush (repeat), rinse with distilled water, drain and fill. All steps should include the overflow reservoir.
minimum .. just drain the radiator + overflow reservoir

In reality one should use the coolant tester and see the condition of the coolant. Most likely partial refresh by draining the radiator would be adequate. Now if there has been some contamination then a flush + rinse may be the better option.

Salim

 

If you insist on going old school and flushing it all out (I remember those days)
Look at this thread which shows the engine block etc drain plug locations on the 2GR-FE engine (which is used in many Toyota & Lexus vehicles)
https://www.clublexus.com/forums/rx-...locations.html

This Toyota Highlander thread may also be useful:
https://www.toyotanation.com/threads...cement.828482/

and this one
​​​​​​https://www.toyotanation.com/threads...how-to.356546/