Cosmoline was sprayed onto all Z engine bays before being shipped to the US. This is a rust retardant but can easily be removed.
There are many different ways offered by members of TT.net but I recommend taking the safe approach. Do not steam clean your engine! There are too many delicate engine components that can be damaged through that process. Take some citrus based cleaner which you can buy at Home Depot or Lowe's for $2/bottle and start spraying. You can use a variety of detail brushes to work it in, and I even use inexpensive paint brushes to get into some tight areas. I then use a spray water bottle to wash it off. It will take some time but you will love the result! Good luck.
