Oil Catch Cans

Finding oil deposits in your intake or intercooler after hard drives? An oil catch can sits in the crankcase ventilation and collects oil mist and condensation before the gases are routed back into the intake. Here you will find both universal cans and vehicle-specific kits.

What does a catch can do?

During combustion, some gas is forced past the piston rings and down into the crankcase. The ventilation routes this gas back to the intake, and it can carry oil mist with it. A catch can sits in between and lets the oil separate out in the can, so less ends up in the intake, intercooler and combustion chamber. How much it captures depends on the internal design and the engine's ventilation. See also PCV valves and air-oil separators.

How to choose a catch can

• Separation: baffles or filter media inside typically affect how effectively the oil is captured. Volume alone does not decide it.
• Connections: hose diameter and fittings must match your ventilation, e.g. 10AN ports as on the adapter from Radium Engineering.
• Draining: a drain valve or drain kit makes emptying easier.
• Space: the can must be mounted securely and away from hot parts.
• Vehicle-specific or universal: vehicle-specific catch can kits, e.g. from CORSA Performance, in several cases come with mounting brackets. Universal solutions are available from e.g. Mishimoto, Moroso and Cusco.

Installation and maintenance

The catch can is installed in the hose between the crankcase breather and the intake. A closed system, where the gases are routed back into the engine, is normally the solution for road cars. Venting directly to atmosphere may be against the regulations, so check this for the specific product and your car. Empty the can regularly, more often after track days and in cold weather, when more condensation typically collects, and check the hoses for leaks.

Frequently asked questions

How often should a catch can be emptied?

It depends on the engine, driving and temperature. Check the can often at first so you learn how quickly it fills up. Empty it more often with track driving and in cold weather, when more condensation typically collects.

What is the difference between a catch can and an air-oil separator?

Both separate oil from the crankcase gases. A catch can collects the oil in the can, which you empty yourself. Some separators are built to return the oil to the engine. It depends on the specific product and its connections.

Can a catch can cause problems at vehicle inspection?

It depends on the product and the car. A solution that routes the gases back into the intake typically keeps the closed system, while venting to atmosphere can cause problems. Check the approval for the specific part number.