[Jon89]

I do an ATF drain-and-fill every 30,000 miles on my 2013 3.6R using either the proper Subaru or Idemitsu ATF. A single drain-and-fill replaces 4.5 to 5 quarts of ATF, right at half the fluid in the system. It is an easy 15-minute job and well the worth the time and money in my opinion.

 

[Jon89]

Yep, first things first. Do an ATF drain-and-fill. Quick, easy, and cheap.