There isn’t a single universal part number for the E30 325i oil filter; the M20 engine uses a cartridge-style filter inside a canister and the exact code can vary by year, market, and supplier. To be sure, check your vehicle’s VIN against a current parts catalog or ask your parts dealer for the precise replacement.
Overview of the oil filter system in the E30 325i
The E30 325i typically uses a canister housing with a replaceable filter cartridge. The cartridge is the consumable part you replace during service, while the housing stays the same. Because different manufacturers and production years use different catalog numbers, the exact part code for the cartridge can differ even for the same model.
Engine variants and filter types
During the E30’s production run, the 325i most commonly used the M20B25 engine in many markets. Some regions offered variations that could influence catalog listings, so the cartridge part number you see in catalogs may reflect the engine code (M20B25) and market rather than a single universal BMW code. Always verify by engine code and year when searching for a replacement.
How to identify the exact part number
To ensure you buy the correct filter, use these methods:
- Read the markings on the currently installed filter cartridge for the exact part number or model name.
- Enter your VIN in a reputable parts catalog (RealOEM, BMW official parts portal, or your dealer’s system) to pull the exact replacement code for your car’s trim and year.
- Verify the filter housing size and thread fitments if you are ordering a cartridge separately from an aftermarket supplier.
- Consult a trusted parts retailer or BMW dealer to confirm the correct number before purchase, especially if you are mixing brands.
Using these steps helps ensure the filter you order matches the original hardware and engine requirements, avoiding fitment or filtration issues.
Where to find reliable cross-references
Several manufacturers and retailers publish cross-reference data so you can match a BMW oil filter cartridge to equivalents from brands such as Mann-Filter, Mahle, Bosch, Wix, and others. The exact cross-reference you see in catalogs may depend on whether you are shopping by OEM part number, by engine code, or by filter dimensions.
- OEM and dealer catalogs: RealOEM, BMW official parts portals, and local dealer systems.
- Major aftermarket brands: Mann-FILTER, Mahle, Bosch, Wix; look for cartridges compatible with M20 engines and the E30 325i.
- Independent retailers: Pelican Parts, FCP Euro, AutohausAZ, and similar outlets often provide cross-reference lists and fitment notes.
When shopping aftermarket, always confirm it is the cartridge-type filter intended for a canister housing on the M20 engine and that the seal/adapter matches your housing.
What to buy and installation notes
Most owners replace only the cartridge element and reuse the existing housing. The replacement process is straightforward: relieve oil pressure, remove the housing cap, replace the cartridge, reseal, and reassemble with fresh oil. Follow the factory-recommended oil grade for the M20 engine (commonly 10W-40 or 5W-30 depending on climate and age) and replace the drain plug crush washer as needed. Dispose of used oil and the old filter responsibly.
Summary
In short, there isn’t a single fixed part number for the E30 325i’s oil filter. The correct code depends on the engine variant, market, and supplier. Start with the engine code (M20B25), verify via your VIN in a trusted parts catalog, and rely on reputable dealer or aftermarket cross-references to identify the exact cartridge part number. This approach ensures you buy a compatible cartridge and maintain proper filtration for the M20 engine.