for decreasing I recommend Dawn Dish Washing Soap HOT water...
HOT water rinse
(repeat)
followed by isopropanol/alcohol (displaces the water)
followed by Acetone (displaces the alcohol and evaporates quickly)
just saying,....that's how we do it in the Labs
(soapy water isnt always the easiest thing to use cleaning spots on large items and tends to propagate so keep it contained or the oil pan might be cleaner than you want it)