This customer’s vehicle was towed into our workshop after she found that there is oil mixing with the coolant in the coolant bottle.

The oil cooler is an essential engine component designed to keep modern cars, trucks, and SUVs running smoothly on the roads they travel daily.

The purpose of the engine oil cooler is to allow the engine’s cooling system to remove excess heat from the oil. These types of coolers are usually of the water-to-oil type of heat exchanger. In most vehicles on the road, engine oil is fed to the oil coolers from an adapter that is located between the engine block and the engine oil filter. The oil then flows through the tubes of the cooler while the engine coolant flows around the tubes. The heat from the oil is transferred through the walls of the tubes to the surrounding coolant similar in many ways to the operation of an indoor air conditioning for residential homes. The heat absorbed by the engine’s cooling system is then transferred to the air as it passes through the vehicle’s radiator, which is located in front of the engine behind the grille of the vehicle.

There are a few signs which can show that the oil cooler is faulty and needs replacement.

1. Oil leaking from oil cooler

One of the components that are part of the oil cooling system is the oil cooler adapter which connects oil lines to the cooler itself and another adapter sends “cooled” oil back into the oil pan. Within the adapter is a gasket. If the oil cooler adapter fails externally, engine oil may be forced out of the engine. It will cause a visible oil leak.

2. Oil in the cooling system


Like this customer experienced, if the oil cooler adapter fails internally, you may notice engine oil in your cooling system. This happens because when the engine is running, oil pressure is greater than cooling system pressure. Oil is forced into the cooling system. This will eventually cause a lack of lubrication and can severely damage your engine.

When the engine is not running and the cooling system is pressurized, coolant can be forced from the cooling system into the oil pan. High oil pan levels can damage the engine by the crankshaft slapping the oil as it rotates.
Any of these symptoms will require flushes of both the cooling system and the engine to remove all of the contaminated liquids. The oil cooler adapter, if it is the failed component, will require replacement. The oil cooler will also need to be flushed or replaced.

If you notice any of these signs, make sure to visit your nearest V.A.G Spec Centre.

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