How does Glycol anti freeze in motor oils damage the engine over time?

In order to understand how Glycol anti freeze in motor oils damages the engine we need to look at what happens when the engine coolant mixes with the oil.

This is not the daily occurance of moisture build up and evaporation that occurs due to the engine warming up and cooling down: We’re talking about substantial contamination over a relatively short time. Not only of water, but several other additives that were never intended to lubricate.


Usually you get Glycol anti freeze in the motor oil when a gasket blows or the cylinder head or inlet manifold gasket are damaged. When this happens water and the Glycol anti freeze in motor oils damages the engine.

Why does Glycol anti freeze in motor oils damage the engine?

Because the primary function of antifreeze is to control extreme temperatures and prevent cavitation it has virtually no lubricating properties when mixed with engine lube.

When mixed with motor oil antifreeze coolant causes a thickening of the lubricant, thereby increasing the oil viscosity and reducing the flow to the bearings and top end of the engine. This will lead to boundary conditions in these components thereby compromising the lubrication and protection of components such as camshafts, followers and bearings.

Another reason why Glycol anti freeze in motor oils damages the engine is that it creates an acidic environment within the oil, resulting in corrosion within the system, especially on copper surfaces. The additives within the motor oil will also be compromised, affecting, anti-foaming agents and detergents in particular. This will reduce the life of the engine.

The longer the oil is contaminated the more the Glycol anti freeze in the motor oil damages the engine.

With the added glycol and water in the coolant, filters are blocked, which further reduces the flow and once the bypass pressure is reached the oil bypasses the filter completely. This allows abrasive particles that would normally have been filtered out to remain in the lubrication system, disrupting the lubricating film and resulting in surface damage to components.

Also, Glycol anti freeze in motor oils damages the engine by mixing with oil to form small spheres called oil balls. These 5 to 40 micron globules, are abrasive and cause severe surface erosion. This is typically found on the inside walls of the cylinder, where the oil balls score the wall. If left unattended they can produce surface fatigue and lead to total lubrication failure where components rely on very tight tolerances.

Glycol anti freeze in motor oils also damages the engine by forming black sludge.

With Glycol anti freeze in the motor oil damage to the engine often occurs when black sludge is formed. Sometimes called black mayonnaise, this thick gel or emulsion restricts oil flow as it moves throughout the engine.
The sludge sticks to the walls and narrows passageways, interfering with oil flow, causing partial or total starvation where the oil is needed. It is very common for glycol and these emulsions sludge to completely block filters, and is reported to be the No. 1 cause of premature filter failure in diesel engines.

There’s not much you can do once there is glycol anti freeze in your motor oil that damages the engine; but once you’ve rectified the cause of the contamination, you need to recharge your lubrication with quality engine oil. Habot Synthetic Lubricants carry a wide range of quality Synthetic lubricants that all have superior detergent properties to keep the internals of your engine the way it should be. Call, and speak to one of our professionals – we are the experts.