So, over the weekend, I did my 15K (now at 45K on new trany) mile, ATF change...
This time I used AMSOIL ATF. Instead of Honda Z1. I used about 2.5 Qrts. Less than 50% of the total capacity of ATF. Should I repeat the drain and refill again, inorder to get to mostly AMSOIL ATF?
Should I try to go all the way (AMSOIL ATF)???
My local Auto Parts store, chargers $12 a qrt. for it...

Now, assuming I go, and do it again...
Is 30K miles, a safe change interval now?

Why not? You're halfway there now, go for it. Even with another drain & fill it will have some Z1 remaining.

You may want to consider doing at least 3 drain/fills with the Amsoil. This topic was talked about over on bitog. The wear results were not good when not doing a full change over to Amsoil. One of the guys has an 02 Accord 3.0 and the other had a 2nd gen Ody.

Here's one of the threads: http://www.bobistheoilguy.com/forums/ubbthreads.php?ubb=showflat&Main=89634&Number=1183919#Post1183919

You may want to consider doing at least 3 drain/fills with the Amsoil. This topic was talked about over on bitog. The wear results were not good when not doing a full change over to Amsoil. One of the guys has an 02 Accord 3.0 and the other had a 2nd gen Ody.

Here's one of the threads: http://www.bobistheoilguy.com/forums/ubbthreads.php?ubb=showflat&Main=89634&Number=1183919#Post1183919

Sence flushing is not good. All one can go is do some extra drain and fills...

Update. I did another drain and fill, at 600 Miles later. This time I did it hot. And tords the end of the drain, I got some extra crud out of the last few drips of ATF. It was black in color, and non metallic. The magnet was almost clean...
I'll probably repeat in the next 1-2K miles...

My observations. Feels like car is torkier, has more pep. And, I do think, I may feel the trany doing things, moor often than before. It has Slightly tighter shifts, especially at part thodle, and I notice the converter-lock-up, slightly moor often...