After 4 weeks the lounge management decided no longer to communicate to Petroleum members that they were no longer allowed to the lounge.
I did not receive an email about htese changes from FB or Petroleum Club, but the lounge management insted I was wrong and that I did receive an email.

Also on various websites it still says PC members are allowed access to the lounge and the lounge management could not come up with the policies.
They were very firm in denying access, which makes PC basically useless for Netherlands-based Petroleum professionals (Shell, Fugro, etc).

With the growth of space for the future lounge I do not see why Petroleum Club and KLM/AF make such an effort to estrange PC members from them.