You'll get almost as many responses as riders.
I use Rotella with 20% ATF. But I have a Rekluse and that combo has given me the best results on 5 bikes.
http://www.gasgasrider.org/html/gear_oil_evaluation.html
I use Amsoil 0W40 and am happy with it.
I've tried motul transoil, motul transoil expert, gro synth, castrol mtx, motul 7100, castrol ATF, silkolene synth gear oil, delo 400, bp farm oil and belray gear saver in my 2011 and 13 300s.
I made the switch to Shell Rotella T last year. Much less expensive on the pocket book and works great. I have been buying the 18.9 liter pales on sale for $3.00 a liter.
What's the capacity in an 01 EC200? 1L as well?