Oil sludge
Oil sludge or black sludge is a gel-like or semi-solid deposit inside an internal combustion engine, that can create a catastrophic buildup. It is often the result of contaminated engine oil and occurs when moisture and/or high heat is introduced to engine oil.
Causes
Oil sludge may occur due to a variety of different factors. Some of the most common causes are:- Defective crankcase [ventilation system]
- Oil/coolant contamination
- Neglecting oil changes
- Low oil level
- Poor engine design