Greetings all,    Recently acquired several post war 4-8-4 turbines and 4-6-4 locos that were very dirty and some with what appears to be white oxidation on the outside of the shells.   Tried several things to clean them but nothing seems to work, especially with the oxidation or white deposits.  It eventually re-appears once dried.    Is there a secret to cleaning off the outside shell, possibly something oil based?
Thanks in advance for your help.    Dave