Energy Insider Summer Edition 2023 | Page 2



The typical internal combustion engine has a water-cooled , four-stroke design using three circuits of working fluids : combustible air-fuel mixture , water-based coolants usually containing glycol , and motor oil used for engine lubrication . All three systems are vital and should never be allowed to intermix . But , at least one original equipment manufacturer says that more than 40 % of catastrophic engine failures are caused by coolant leaks and cross-contamination . Coolant contamination of lubricating oil occurs most often when a gasket blows or the cylinder head or inlet manifold gaskets are damaged .
Engine lubricants can handle “ normal ” moisture levels caused by condensation due to the engine warming up and cooling down . Small of amounts of water simply evaporate away . But catastrophic failure happens when there is substantial contamination over a relatively short time . Contamination with antifreeze involves not only the water portion , but also several other additives that were never intended to lubricate .
When mixed with motor oil , antifreeze / coolant causes a thickening of the lubricant , thereby increasing the oil viscosity and reducing oil flow to critical engine parts . This leads to boundary conditions in which metals are no longer separated by a thin film of lubricants , resulting in friction and wear .
Coolant contamination in motor oil can also damage the engine by creating an acidic environment within the engine , resulting in corrosion . The additives in the motor oil become compromised , and performance is negatively impacted . When glycol contaminates engine oil , the result is formation of what ’ s commonly referred to as “ black sludge .” The gooey , thick gel restricts oil flow as it moves throughout the engine . It is common for glycol and sludge emulsions to completely block filters , which is reported to be the leading cause of premature filter failure in diesel engines .