Thermostatic vs Non-Thermostatic Oil Coolers: Which One Should You Pick?

Oil cooler – primarily, you can consider it something that keeps oil cool. In short, it dissipates the excess heat generated while the engine is on. You cannot ignore its importance as it protects engines from getting too hot and restricting them from maintaining performance. Now, when we talk about oil coolers, a good confusion appears – thermostatic vs. non-thermostatic oil cooler.

Thermostatic oil coolers offer a controlled cooling environment. They allow oil to bypass the cooler until it reaches a specific temperature. In this way, they ensure faster engine warm-ups and protection in cold climates (1). Alternatively, non-thermostatic oil coolers provide continuous oil flow to the cooler. These coolers are ideal for heavy track use where maintaining lower oil temperatures is critical (2).

Well, both are two common categories of oil coolers, yet they mainly serve the same purpose. They lubricate the engine’s moving parts, reduce friction, and dissipate heat. Still, these two items have some significant differences. Today, I’ll discuss them in this article. I guess you won’t want to miss reading it.

Thermostatic vs. Non-Thermostatic Oil Coolers: Primary Differences

For sure, I do not want to waste your precious time. So, I am explaining the first type of oil cooler now.


Can you remember the thermostat in your refrigerator? Hence, thermostatic coolers incorporate a built-in thermostat like those in freezers. It acts as a switch for the oil cooler. This switch prevents cold oil from flowing into it. It allows warm oil into the cooler once the engine oil reaches full operating temperature (3).

Let me talk about the design.

Well, the design of thermostatic oil coolers resembles a small crossflow heat exchanger with several connected tubes. They allow the oil to release excess heat before returning to the engine.  Hence, hot oil circulates through tubes equipped with fins that release heat. Then, the processed oil exits the cooler.


So, you have learned about thermostatic oil coolers. Now, I will explain coolers that are not thermostatic.

As the name suggests, non-thermostatic items do not have a built-in thermostat. More precisely, these components do not wait for oil to reach certain temperatures. They always work for sure. If the oil cooler does not allow the oil temperature to exceed 212°F, condensation may build up in the oil. It will make you think and may make you call an expert mechanic (4).

Besides, these coolers may cause the oil to take longer to reach its optimal operating temperature, especially during short journeys or in cold weather.

Whatever the oil conditions, these non-thermostatic oil coolers are designed to work (to cool oil) all the time. Like thermostatic, these coolers are typically a crossflow heat exchanger with a series of connected tubes (5, 6).

Differences of Advantages

Thermostatic Oil Coolers

Certainly, thermostatic oil coolers offer multiple advantages. Some of them are:

Thermostatic oil coolers contribute to a faster engine warm-up. It is particularly beneficial in cold climates. Again, the sandwich plate with an oil cooler protects the oil system.

Utilizing an internal wax element, it reads the temperature of the incoming oil. It diverts it to the cooler if necessary. This mechanism prevents the engine oil from overheating by opening partially at 215°F and entirely at 230°F (7).

The thermostat can divert oil to the cooler based on temperature. Usually, it is a 185°F thermostat, which can be swapped out for either a 160°F or 200°F unit. It allows for customization based on specific needs or preferences. Also, it keeps the oil temperature below a certain range that can damage the engine (7).

Integrating oil coolers into the lubrication system of engines leads to enhanced cooling. It can improve engine performance, increase oil longevity, and improve fuel economy (8). Moreover, these parts keep the oil temperature within optimal ranges and extend the life of the engine’s moving parts. So, you can reduce maintenance costs and enhance the reliability of the engine.

Non-Thermostatic Oil Coolers

Like thermostatic, you can also experience several paybacks from non-thermostatic oil coolers. For instance, these coolers are considered ideal for heavy-track use. They provide continuous oil flow into the cooler. It is crucial for maintaining optimal engine performance under high-stress conditions (9).

Again, these coolers operate with an ‘always on’ cooling approach. They are opposite to thermostatic oil coolers as they regulate oil temperature by only allowing oil to flow through the cooler when it reaches a specific temperature. It can be advantageous in consistently high-temperature environments like racing (10).

Functional Differences

I mean how these coolers work – do you know about it? Well, the thermostatic oil sandwich plate (or the valve) acts as a “switch” for the oil cooler. It contains the thermostat I have already mentioned.

However, the valve’s primary function is to regulate the oil flow through the oil cooler. It controls the opening and closing of oil passages based on the engine oil’s temperature. In this way, this valve ensures that when the oil is cold, it remains closed to direct the oil flow directly to the engine (11).

These functions are adequate for engines using the pressure screen system and those with a full-flow oil filter (12).

Surprisingly, racing cars’ high-flow engines have unique oil cooler thermostat. It accelerates fluid warm-up time. Also, it can maintain a minimum fluid temperature with a patented design. This design avoids valves, springs, or other obstructions in the primary oil flow (13).

Compared to other ones, operating a non-thermostatic oil cooler is relatively straightforward. Even if the engine is cold, it allows the oil to flow into it consistently. Hence, the oil enters it and circulates through tubes. After cooling, the oil goes out of the cooler at a temperature that is already colder.

Common Issues and Troubleshooting: Thermostatic vs. Non-Thermostatic Oil Cooler


Some common issues with thermostatic oil coolers are:

  • A stuck-open valve allows excessive coolant flow to the oil cooler. As a result, the oil temperature goes down.
  • Stuck-closed valve restricts coolant flow, causing the oil temperature to rise.
  • Reduced coolant flow can lead to engine overheating and oil degradation.
  • Increased coolant flow can result in poor fuel efficiency and reduced engine performance.
  • Oil or coolant may leak from the oil cooler.

When you see any above issues, you may try these solutions:

First, check for any visible oil leaks around the valve or oil cooler. Then, inspect the valve for any signs of damage or corrosion. Also, test the valve’s opening and closing mechanism by applying heat or cold to the wax-filled element and observing its response. Next, measure the temperature of the engine oil using a suitable tool. In this way, you can ensure it is within the recommended range.


You may get some issues with non-thermostatic oil coolers like these:

  • These coolers can cause the oil to overheat if the engine carries high loads for extended periods.
  • Oil may take longer to reach its optimal operating temperature for these coolers. It may become more notable, especially during small journeys or in winter.

You may apply these solutions:

Like the previous one, check the oil cooler for any signs of damage or leaks. Next, clean the oil cooler regularly to prevent the buildup of debris or contaminants. Also, regularly check the oil pressure and temperature to ensure the oil cooler functions properly. If the oil temperature is consistently high, it may indicate a problem with the oil cooler.

Final Words

Now, you can choose which one you want. I have explained everything regarding thermostatic vs. non-thermostatic oil coolers.

A thermostatic oil cooler will be better for you If you drive for a long time (especially in cold climate conditions). Otherwise, choose a non-thermostatic one for continuous cooling. Yet I do not recommend these if you remain in areas where it is cold almost yearly.

Thank you for reading this article.

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