Hello
I do know and some slight heat will speed up there.
Wait until you have to remove the things on the underside of the pan.
If you have to much to do to pack it in a working day you must find a way to save time. Costs aren´t interessting then. Better 2-4 concentradet hours then 2-4 work days in dust and dirt. Other do hot tank or use plastic blasting. Both ways have other benefits but you have to organize it and pay the company. And mostly after that you still have to sandblast the rust away.
Read all about the noisy and loud 959, the prototypes had been so loud that you even couldn´t hear the engine ideling inside, so after Karajan complied about missing some music they made the cars a bit noisier:
http://www.911turbo.com/turboclub/history/history.html
Grüsse