You may have heard that an oil separator should be one of the first mods to get for your Mustang. And more often than
not, that’s completely true. Oil separators, or catch cans, can prevent potential oil buildup in the intake manifold of
What Causes Oil in the Intake Manifold?
As the combustion process occurs in the cylinder, some of the air can leak past the piston. When the air goes past the
piston and into the crankcase, it’s called blowby. This can cause pressure to build up within the crankcase along with a
mixture of air, oil, fuel, and contaminants.
As part of the Mustang’s positive crankcase ventilation (PCV) system, valves are attached to the crankcase to let the
pressure and air escape. Think of it as a way to recycle unused gas fumes. However, the valves can pick up the oil at
the bottom of the crankcase, rerouting the contaminated air back to the intake.
When these oil vapors go through the PCV system back into the intake, oil can coat the intake valves, linings, interior,
and throttle body. Oil and gunk buildup can reduce engine efficiency, resulting in a loss of power, diluted gas, and a
lowered octane level.
This can happen in a naturally aspirated engine, although the chances are higher in a turbocharged or supercharged
How Do Oil Catch Cans Work?
Oil catch cans connect to the PCV system and filter out contaminants in the air before it is sent to the intake
manifold. They use a system of filters and baffles that collect the oil and trap the contaminants. Oil separators
typically have two hoses. The first hose connects to the port off the crankcase, sending the contaminated air to the
catch can. A second hose then sends the filtered air onward to the intake manifold.
What are the Benefits of an Oil Catch Can?
By installing an oil separator on your Mustang, you’ll prevent the intake tract from getting caked with oil. An
oil-caked intake tract can result in reduced efficiency and is a safety hazard.
Without an oil separator on a car that spends a fair amount of time in high RPMs, oil can build up around the throttle
body. This can cause the throttle body to trip a check engine light due to lack of response. The throttle body could
also potentially get stuck open or closed, which isn't a good thing.
Here are the biggest benefits of installing an oil catch can:
- Keeps blowby out of the intake manifold
- Prevents carbon buildup on the intake valves and tops of the pistons
- Reduces chance of engine knock and ignition failure
- Improves engine efficiency by preventing buildup
How Often Should You Empty an Oil Catch Can?
An oil separator will filter out oil and collect it in a small reservoir for easy maintenance. It’s recommended that you
check the catch can every 1,000 miles after initial installation to gauge how often it will need to be emptied. Some
driving styles may warrant a check more often than others. Once you find a schedule that works for you, you’re good to
For a regular street car, it’s common to check the oil separator every 3,000 miles. For Mustang drag cars, it’s
recommended that you empty the catch can at the end of each run. Keep in mind that the larger the reservoir, the more it
will hold. Always check the manufacturer’s instructions for a more detailed maintenance schedule.
Is an Oil Catch Can Necessary?
Oil catch cans aren’t a necessity, but any way you can protect your engine is worth considering. If you’re not doing
much performance driving, they may not be as important. But if you plan on doing any aggressive driving or have a
high-powered engine, an oil catch can is a smart upgrade.
Even if you have a factory catch can, upgrading to an aftermarket oil separator can improve performance since they’re
better at trapping contaminants.
What Other Vehicles Can Use Oil Separators?
Oil separators are good for any vehicle with a hard-working engine or those with a forced induction system. Along with
Mustangs, they make great additions to the Ford Focus ST, F-150, and F-150 Raptor as well as the Jeep Wrangler and
Gladiator. They’ll help keep the intake system nice and clean for optimal performance.
Source: Engineering Explained