On the ATF, I used to have a 87 euro spec Mercedes 300D 6 Cylinder non turbo, when I added a half pint ATF to a full tank the injector knock/rattle was much less after treatment - in fact when the engine was warm it was almost as quiet as a gasser.
I added ATF several times a year and never seemed to cause any problems and made it smooth and quiet.
Interesting article - I think I will find some opti lube for my B21 too.