Engine Oil Overflow Tank

What Is an Engine Oil Overflow Tank?

An engine oil overflow tank — sometimes called an oil breather tank or oil catch tank — is a small reservoir designed to capture oil vapors, blow-by gases, and excess oil that escape from the crankcase breather or dry sump system vent. Without one, those vapors and oil droplets are either vented to the atmosphere or routed back into the intake, where they can foul components and reduce engine efficiency. In performance and racing applications, where elevated RPM and aggressive tuning push crankcase pressures far beyond street-car norms, a dedicated overflow tank is an essential part of a clean, reliable oiling system.

Why Engine Oil Overflow Tanks Matter

In high-performance engines — whether on a circle track, a drag strip, or a road course — crankcase ventilation demands increase dramatically. Dry sump systems, vacuum pumps, and high-winding race engines all generate elevated crankcase pressure that must be managed. An oil overflow tank gives those vapors a controlled place to go: oil is separated and collected, while clean air is vented away. The result is a cleaner engine bay, reduced risk of oil on the tires, and consistent oiling system performance lap after lap. For sanctioned racing, many tech rules also require that overflow tanks be present to prevent oil from being deposited on the racing surface.

What to Consider When Shopping

• Capacity: Most race applications use tanks in the 1–2 quart range, but dry sump and high-displacement engines may demand more volume.
• Material: Aluminum tanks offer durability and a clean appearance, while polyethylene or plastic tanks are lightweight and cost-effective.
• Fittings: Match inlet and outlet thread types (NPT or AN) to your existing plumbing for a leak-free installation.
• Mounting: Look for tanks that include brackets or have a compact form factor suited to tight engine bays.
• Venting: Some tanks feature filtered breathers that trap oil mist while allowing air to escape freely.

Top Brands in Engine Oil Overflow Tanks

Moroso Performance Products is the category leader and a name synonymous with serious racing hardware. Moroso is one of the world's most respected suppliers of automotive equipment for racing and street performance, manufacturing over 4,000 items including oiling systems, oil pans, and related components. Their oil breather tanks are purpose-built companions for racing vacuum pumps and dry sump systems, featuring aluminum or polyethylene construction with NPT or AN fitting provisions and a non-hooded clamp-on breather that traps oil while allowing air to escape.

ATI Performance Products brings decades of drivetrain and engine accessory expertise to this category. Known primarily for their Super Damper harmonic balancers and torque converters, ATI's engine oil overflow tanks are engineered to the same exacting standards that professional drag racers and road racers have relied on for years.

Jaz Products is a well-regarded name in circle track and oval racing, offering a broad selection of overflow tanks that balance function and value. Jaz's lineup covers a wide range of sizes and configurations, making them a popular choice for grassroots racers building on a budget without sacrificing reliability.

Billet Specialties brings a premium, show-quality aesthetic to functional racing hardware. Their overflow tanks feature clean billet aluminum construction that looks as good in a show car as it performs in a race car, appealing to builders who demand both form and function under the hood.

Howe Racing Enterprises has a long heritage in circle track racing components. Their overflow tanks are built with the rigors of oval racing in mind, offering straightforward, race-proven designs trusted by short track competitors across the country.