Couple words of advice. Unless you need to flush your coolant, there’s no need to drain the system. Just place a line clamp on the coolant hoses.
Do not remove the intake manifold completely. All that’s needed is to pull it away enough to access the hidden bolt for the OFH.
You’ll need new O rings for the oil cooler lines.
The coolant hose coming from the tstat to the OFH…the plastic fitting on the end of the hose is prone to break. Rein makes a metal replacement
https://www.fcpeuro.com/BMW-parts/Z3...ywords=Chc0609
Good luck