What Kinds of Oil Are Used in Radiators?

A range of different oils.

Radiators are a necessary part of life just about anywhere that gets even reasonably cold. And, just as any tool should be understood by those using it, it’s pretty important to know what’s going in to your radiator before you actually start it up. Why is pretty obvious: Heating an entire home requires a lot of energy, and mishandling that much energy can lead to some serious problems. Fortunately, radiators are fairly easy to understand, and can be divided into two classes: There are water-based radiators, and oil-based ones. Most newer radiators are oil-based, as they tend to be safer, easier to make, and easier to maintain. Of course, the details of your home’s construction and the radiators precise location can change things; older homes tend to have water radiators, for instance, and car radiators are almost always water. Both function in totally different ways, which we’ll cover briefly here, before discussing the most common oils that you’ll find in oil-based radiators. Understanding these things isn’t all that hard, but it is important: We hope you’ll walk away with a working knowledge of radiators at the end of this.

Water Based Radiators: An Overview

Water based radiators are the older type of radiator, and, in some sense, are simpler, as well. They’re almost always high-pressure vessels that contain a good amount of water. The radiator transfers heat energy to the water, which acts as a heat reservoir, and eventually, turns to steam. The high pressure in the tank helps contribute to the rise in temperature and maintain the heightened energy level, thus helping the radiator function optimally.

Because water based radiators are high-pressure beasts, it usually takes a trained technician to work with them safely. Doing maintenance to such a radiator in the wrong way can lead to a variety of minor but easy-to-handle complications, such as leaks or whistling; but in the worst case, it can result in explosions, destruction of the radiator’s mechanics, and sever burn related injuries.

Oil Radiators: A Little Safer and A Whole Lot Better

Oil radiators are much safer than water based ones because they’re not dependent on a high-pressure container. The basic principle is similar: The radiator transfers heat to the oil, which stores the heat energy. The difference here is that the oil doesn’t turn to steam, since it’s able to hold a lot more energy than water can (as the chemists and physicists would say, it has a higher heat capacity than water). This heat is then transferred from the oil’s tank to the metal of the radiator, and from there, the air around the radiator gets warm, creating circulation in the room. As this process continues, all of the air in the room gets warmer.

Oil radiators work on the same physical principle as do water based radiators — that is, they are both convection heaters. However, the fact that oil radiators don’t require high pressure tanks or specialized maintenance tends to make them a far better choice for most homes. Taking care of them is easy, since the worse that can happen is a leak or connection mistake that prevents the radiator itself from absorbing heat from the oil, both of which are easy to fix on your own; and replacements of the oil can be done with virtually no issues, as well.

What Kinds of Oil Go Into the Radiators?

The kinds of oil that go into the radiator can vary widely, depending on the details of the radiator’s function. Those that pump huge amounts of energy into the oil (like the radiators you’ll find in lecture halls and other large buildings, for instance) need one with an exceptionally high specific heat capacity, most of which are custom-synthesized by chemical companies specializing in organic compounds that can serve as heat reservoirs. Such oils are typically sold under brand names, such as Thermoil or So(i)lstice. Smaller, home-based radiators can typically function with high smoke point vegetable oils, however, and many are designed to work with recycled cooking oils that can be picked up from local restaurants, or distributors that collect from local restaurants for you. This makes for an easy heating solution that’s all at once more efficient and more sustainable than the alternative of water radiators.

With that said, it is important to remember that a lot of the oil filled radiators on the market these days are sealed units that come with their own supply of oil, so you will never need to access it or “change the oil”.