does anyone know how to install a pcv valve o ring [oil seperator] on the right rear of a 1998 mazda mpv 3.0 engine?

PCV means Positive Crankcase Ventilation. Intake manifold vacuum sucks air out of the engine, air replaced from a hose back to crankcase after passing through air filter for intake. The valve prevents air from going the wrong way, pushing air back in to intake, especially important on positive pressure induction systems, i.e. supercharged. I don't know what you mean by 'oil seperator'

Do anyone know where is and how to replace a pcv valve o ring (oil separator) on a 1997 Mazda mpv 3.0