Things you must know about engine oil cooler

As cooling is vital in an engine to absorb hotness, the oil cooler is a device that is used to take care of that. Oil cooling is the use of engine oil as a coolant to remove excessive heat from internal combustion engines.

Keeping engine components at their normal working temperatures improves performance and extend service life. There should be serious consideration on the oil cooler, though professionals in the field focus on cooling various drivetrain components.

In automobiles, hot engine transfers heat to the oil which latter-on passes through a heat exchanger. This heat exchanger is generally a type of radiator that has been named “oil cooler”. After the hot oil flows through this component and cooled, it then recirculates to absorb the engine’s hotness again.

oil cooler functions

Today we’ll be looking at the definition, functions, types, working, diagram, advantages and disadvantages of an oil cooler used in an automobile engine.


Oil Cooler Definition

An oil cooler is a mechanical device that is used to remove surplus heat from internal combustion engines through a heat-exchanger. The device is used for cooling various mechanical parts using oil. These parts include engine, transmission system and etc.

The oil cooler is in the form of a small radiator located in front of the water-based radiator system. Its primary purpose is to lower the temperature of the vehicle while running. That’s the component works only the vehicle is running. The cooled oil serves a lot of purpose to the high-stress transmission oil. Engines with cooling fans rapidly cool both the water- and oil-based radiator, which is why offer additional benefits.

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Because oil cooler function as an additional cooling device, its application to air-cooled engines will dramatically reduce the high temperature. The life of the engine will drastically be increased. Heavier trucks make good use of oil cooler which help to put more strain on the drive train.

The enhancement of cooling efficiently keeps heated engine oil working at cooler temperatures and also reduces the chance of premature breakdown. The breakdown of oil loses the ability to lubricate and to act as a coolant.

Types of Engine Oil Cooler

Engine oil cooler can be generally classified into two types such as oil-to-water and oil-to-air.

Oil-to-water cooler: in these types of oil coolers, the coolant passes through a heat exchanger element of some parts. The coolant is enabled either by adding heat to cold oil or draw heat from excessive hot oil.

Oil-to-air cooler: is a small radiator that enables the engine oil to be cooled directly from an ambient air from the cooling fans. Most of the oil-to-air coolers work with a thermostatically controlled bypass valve that stops the engine oil from passing through the cooler without reaching its desired operating temperature.

The various types of coolers include the basic tube-and-fin style, where the oil is passing through a single or multiple coolers. Some other types may have multiple cooling rows or have a stacked-plate type. Some oil coolers are header-style, where the end tanks are designed like a radiator.

Working principle of an oil cooler

In the working of oil-to-air coolers, they are usually mounted in front of the radiator, although they are of the same shape. This gives the engine oil quick access to coldest fresh air from the cooling fan. In most cases, the oil passes from the engine in the form of a “sandwich” adapter.

This adapter is mounted between the oil filter and the engine block as it allows hot oil to flow through the filter. It then passes through the oil cooler before going backing to the engine for the same process. some of these sandwich adaptors are designed with thermostatic control that disabled oil from flow until it reaches a specific temperature.

Some systems are designed with remote that is a mount for oil filter and an additional adapter that uses the existing oil filter. The existing oil filter mounts to plumb hoses to the cooler and the remote filter base.

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There is often an inline thermostat that offers same bypass function. In vehicles where there is no space to mount at the front of the radiator, manufacturers provide coolers elsewhere in the engine. Some even feature their own cooling fan. This design is much like the dry-sump lubrication system.

Watch the video to have more understanding of the oil cooler system:

Advantages and Disadvantages of Oil Cooler


Below are the benefits of oil cooler in an internal combustion engine:

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  • With a thermostat, oil cooler cools hot oil at an exact temperature.
  • It ensures proper cooling of oil before circulating.
  • The temperature of the oil is controlled in the oil-to-water cooler.
  • Installation of oil coolers is quite easy.
  • Generally, oil cooler enhances the working of an engine.
  • It decreases the use of water cooling system as it can be corrosive to the engine.
  • As oil drastically serves as a coolant, extra coolant tanks, pumps, radiators are eliminated from the engine design.
  • Oil circulation is efficient and controlled.


Despite the good advantages of an oil cooler, some limitations still occur. Below are the disadvantages of the engine part:

  • Unlike water, the oil may be flammable.
  • Extra oil is required to operate the oil cooler.
  • Extra maintenance is must be done.
  • Thermostat failure will stop the circulation of oil, especially if permanently lock.
  • Over cooling may occur if the valve is permanently open.

Symptoms of a Bad or Failing Oil Cooler

Below are the various symptoms of a bad oil cooler and their prevention:

oil cooler types

Leakage of the oil cooler adapter:

There is two Oil cooler adaptor in the system, one connects oil lines to the cooler itself. The other sends cooled oil back into the oil pan. The oil cooler adaptor may fail externally, which may lead to forcing out the engine oil out of the engine.

If the leakage between the adapter is small, then the driver may notice a puddle of engine oil at the bottom part of the engine. There is a possibility to see a stream of oil on the ground behind the vehicle.

You should see your professional mechanic if you see any oil leakage under your engine. The problem can be easily determined and quickly repaired. Serious care should be taken on this leakage failure because the engine as a whole loses full lubrication. This issue could result to increase in the engine temperature and premature wearing of the parts.

Oil in the cooling system:

The oil in cooler adapter may fail internally as you will notice the oil pressure is greater than the cooling system pressure. This occurs when the engine is running, causing the oil to be forced into the cooling system, resulting in a lack of lubrication. The problem can cause intense damage to the engine if care is not taken.

Leakage of engine coolant from oil cooler:

This failure is similar to the first one, caused by an external oil cooler failure to force all the engine coolant out of the engine. whether the leakage is small or large, overheating will eventually occur if issue not fixed.

Larger leakage will waste all the coolant as you will notice a stream of oil pouring out from under the hood of the vehicle. you’ll also need to immediately contact your mechanic in this situation.

Coolant in the oil:

This issue happens when the engine is not running and the cooling system is pressurized. The coolant can be forced from the cooling system into the oil pan. High oil pan levels can damage the engine as the crankshaft slapping the oil as its rotates.

Bad thermostat:

A bad thermostat will either cause overheating or undercooling to the engine. the thermostat is a device that controls the flow of oil into the oil cooler, it opens at a specific temperature of the oil.

If the thermostat fails when it’s close overheating occur because oil circulation stops eventually. And if the thermostat fails when it’s open undercooling occur because the oil keeps flowing continually without absorbing the heat.

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In conclusion, we’ve seen that oil coolers assist the engine lubrication system as it removes surplus heat from the engine parts. We examined the working, functions and types which include oil-to-water and oil-to-air cooler. Oil cooler advantages and disadvantages were also revealed.

I hope the knowledge is attained, if so, kindly comment, share and recommend this site to other technical students. Thanks!

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