I recently became the proud owner of a ZF6 equipped Duramax, and as any new owner should I decided to change all the fluids. Trying to find trans fluid that is TES-295 rated turned out to be a little difficult. What I found is that Royal Purple Max ATF fluid is TES-295 rated and luckily for me, stocked at the local Napa. I just got back from a test drive after changing the fluid, so far the Royal Purple is working great, the trans shifts much smoother than it did before. Just wanted to share what I found for the few ZF6 owners out there.