The classics are junk at $130 oil. The only reason some are still flying is because the shippers are desperate for the capacity and are willing to foot the fuel bill. I think the hourly rate for a -200 is down close to $4000, probably less than that now. Maybe some others with more direct current info will have a more accurate figure.
It wouldn't be beyond belief to think that the ACMI carriers are skimping on mx in order to try and at least break even.