I'm thinking my next exchange will be at 40,000. The car will be out of warranty and I'm thinking of going with Amsoil ATL. I'll probably drop the pan again and check and see how things look, while changing the filter once more. After that service, if all is well, the next one will probably be a drain and fill after about 30,000 and perform pan drops every-other service. That is:
10,000 - Pan drop, filter replacement and an attempt at a full exchange by disconnecting cooler line and refill with Toyota WS
40,000 - Pan drop, filter replacement and an attempt at a full exchange by disconnecting cooler line and refill with Amsoil
70,000 - Drain and refill with Amsoil
100,000 - Pan drop, filter replacement and an attempt at a full exchange by disconnecting cooler line and refill with Amsoil
I'm gonna be checking into the Amsoil ATL a little further. If I remember correctly, I read somewhere on here that with the Amsoil, there was more wear elements in the UOA than with the Toyota WS in this application. In other applications, UOA's show the Toyota WS being somewhat "spent" at 30,000-40,000 miles, so I will at least adhere to this interval. So much for the "lifetime" fluid.