Oil Catch Cans: Why You Might Need One for Your Vehicle?

With so many oil catch cans available for vehicles nowadays, it’s easy to feel overwhelmed by conflicting advice online. This guide aims to provide clarity on the function of oil catch cans, helping you decide whether installing one in your vehicle is the right choice. Whether you’re interested in the technical details or just want to know if you should invest in a catch can, this breakdown will help you make an informed decision. 

What is an Oil Catch Can?

An oil catch can (aka oil-air separator), functions to capture oil particles from the air passing through the engine’s breather and into the intake system. The question here is: how does oil accrue in the intake system? For this, we need to understand how internal combustion engines function. When the engine fires, some pressure from the combustion process escapes into the crankcase—this is called positive crankcase pressure. As the crankshaft and other parts spin rapidly, oil vapour mixes with air and must be vented out through a system known as the positive crankcase ventilation (PCV) valve. Although these oil vapours are required by emissions laws to be re-circulated back into the intake system, over time, this can lead to oil build-up, which is where oil catch cans come into play.

How Does a Catch Can Work?

A catch can is fitted between the positive crankcase ventilation valve and the air intake system. It catches the oil particles in the air that would otherwise re-enter your intake. The installation involves detaching the PCV hose and redirecting it through the catch can. In the catch can, air flows in through the bottom, moves through a filter, and departs at the top. As the air moves, the catch can filter enclosed oil particles, letting them pool at the bottom while clean air moves through to the opening.

Most catch cans, including the popular ProVent 200 catch can kit, are equipped with a drain plug, making it easy to remove the collected oil. Typically, the catch won’t need emptying until your regular engine service intervals.

Why Should You Install a Catch Can?

Modern vehicles often come with an additional emissions system known as Exhaust Gas Recirculation (EGR), which directs exhaust gases back into the engine’s intake system to burn any remaining hydrocarbons before they depart through the exhaust. The downside is that over time, soot and oil vapour mix, creating a thick layer of carbon build-up in your engine’s intake manifold. This results in poor engine performance and requires costly cleaning.

Fitting a catch can help prevent this issue by catching the oil particles before they can mix with the soot. Although some car owners choose to install EGR blanking plates to avoid carbon build-up, this modification is illegal for road use. Installing a catch can is a far better alternative, as it ensures your emissions system stays intact while preventing excessive carbon build-up.

Why Don’t Cars Come with Oil Catch Cans Installed?

If oil catch cans are so beneficial, you might wonder why manufacturers don’t install them as standard. The reason comes down to manufacturing costs and maintenance. Car manufacturers prioritise cost efficiency when producing vehicles in large volumes, and omitting features like catch cans keeps expenses lower. Additionally, the need to regularly empty a catch can add to vehicle maintenance, something manufacturers avoid adding to the list of dealership services.

Problems caused by the lack of a catch can often not appear until after the vehicle’s warranty period, meaning manufacturers don’t bear the responsibility for repairs.

Why Were Catch Cans Not Common in the Past?

Years ago, many vehicles had simple crankcase ventilation systems that vented to the atmosphere. However, as emissions laws became stricter, manufacturers began routing crankcase vapours back into the intake system to comply with regulations. In older vehicles, this wasn’t much of a problem, but with modern engines—particularly diesel engines with high crankcase pressures—the risk of carbon build-up has increased. This is why oil catch cans have become more widely recommended in recent years.

How Do Different Catch Cans Compare?

While any oil catch can is better than none, different brands vary in terms of filtration efficiency, flow rate, and ease of installation. For example, the ProVent 200 catch can kit is designed specifically for 4WD vehicles, making it a top choice for off-road enthusiasts. Be sure to research different models, as each offers unique advantages depending on your vehicle and driving habits.

Can I Install a Catch Can Myself?

Installing an oil catch can could be a rewarding DIY project if you have basic mechanical skills and the right tools. Vehicle-specific kits simplify the process by providing pre-made brackets and hoses for easy installation. However, it’s important to carefully route the hoses and ensure all connections are secure to avoid leaks. If you’re unsure how to install, it’s a good idea to consult a professional technician or book a workshop appointment for proper installation.

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