1. NEVER use silicone on rubber gaskets (it can make them swell & distort).
2. Don't over tighten the rocker cover bolts (I go finger tight then 3/4 turn....no leaks)
3. Your engine has an oil separator (cyclone) not a PCV valve.
4. blocked breather lines will cause you dip stick to pop out due to crank case pressurisation.
5. be sure you have tightened the r/cover nuts evenly otherwise the gaskets won't seal.
HTH!
BMW parts professional
Previous rides:
BMW
E12 M535i (go the dogleg!)
E28 M535i (MMM M88!)
E34 535i M
MAZDA:
RX7 S-IV T04 (440 hp ATW)
RX7 S-I 13b bridge port
RX4 13b peripheral port