Here's my deal... the scum on top is a combo of rust and grease. The solution isn't a degreaser but it does loosen the grease and old paint.



These rocker arm shafts spent over 10 years outside on an engine without valve covers...





The springs are old stockers that will replace the broken one's in my dropped '97 Ram... the bracket is off my dirt late model quick change. Again it was very rusty after 20 years of storage.

The key to this solution is patience.... don't expect haevy rust to disappear in a day. Light 'shelf' rust will dissolve in a few days... heavy stuff may take weeks. just dip it and forget it.