Bosch 3974 Engine Oil Filter

Bosch Premium Oil Filter for Subaru Applications

The Bosch Premium Oil Filter 3974 is built for Subaru engines that need dependable oil filtration and consistent flow. It uses a spin-on design with a 20-micron rating, anti-drain back valve, and bypass relief valve to help keep oil cleaner during everyday driving and cold starts.

Compatible With Subaru Impreza, Ascent, Crosstrek, Forester, Legacy, Outback, WRX STI, XV Crosstrek, WRX, and Baja applications, Bosch 3974 is a practical OE-style replacement for drivers maintaining long-term engine protection.

Key Features

• Spin-on oil filter design for straightforward replacement
• 20-micron filtration to capture fine contaminants
• Anti-drain back valve helps retain oil in the filter after shutdown
• Bypass relief valve supports oil flow if the media becomes restricted
• Cellulose paper filter media with nitrile gasket material
• M20x1.5 inside thread size and connection size
• 2.58 in oil filter height and 2.677 in outside diameter
• 200 burst pressure rating

Detailed Description

Bosch Premium Oil Filters are engineered to keep harmful particles and dirt out of the lubrication system, reducing premature wear and helping protect against engine damage. The Bosch Premium Oil Filter 3974 uses a blend of filtration-focused materials and OE-style fitment to match the installation profile expected on many Subaru engines. Its anti-drain back valve helps maintain oil in the filter between starts, while the bypass relief valve helps preserve circulation when oil is cold or the filter media is restricted. This makes Bosch 3974 a solid choice for Subaru Impreza, Forester, Outback, Legacy, Crosstrek, WRX, and WRX STI maintenance.

This part cross-references Monroe Shocks & Struts (e.g., 172286, 182286) for the same application.

What It Helps Address

• Excess engine wear from dirt and abrasive particles in the oil
• Oil drain-back after shutdown that can delay lubrication on startup
• Restricted oil flow caused by a loaded filter element
• Routine maintenance needs for Subaru oil service intervals
• Protection concerns on high-mileage or daily-driven engines

Installation Notes and Tips

Verify the M20x1.5 thread size and filter dimensions before installation. Replace the filter during each oil service, and pre-lube the gasket with clean engine oil before tightening to the manufacturer’s recommended torque. Confirm the filter seats properly and check for leaks after startup. Fits 1993-2022 Subaru Impreza, N/A; Fits 2019-2021 Subaru Ascent, N/A; Fits 2016-2021 Subaru Crosstrek, N/A; Fits 1998-2021 Subaru Forester, N/A; Fits 1990-2021 Subaru Legacy, N/A; Fits 2000-2021 Subaru Outback, N/A; Fits 2013-2020 Subaru WRX STI, N/A; Fits 2013-2015 Subaru XV Crosstrek, N/A; Fits 2008-2014 Subaru Impreza, N/A, Color Code Blue; Fits 2013-2014 Subaru WRX, N/A; Fits 2013-2014 Subaru WRX STI, N/A, Color Code Blue; Fits 2011 Subaru Forester, N/A, From 04/2011; Fits 2003-2006 Subaru Baja, N/A.

Quality Assurance

Bosch Premium Oil Filters are built to support high-performance engine protection and long service life through controlled filtration and OE-style fitment. Bosch 3974 is designed for consistent oil filtration performance in Subaru maintenance applications.