BMW M56 Engine Guide

The M56 is a 2.5 liter inline-6 sold only in US-market BMWs, a re-engineered version of the M54B25 built for the E46 325i and 325Ci. Wikipedia says it was BMW's first SULEV (super ultra low emission vehicle) engine and that the cars were sold in California, New York and Massachusetts as 2003 models and in Vermont from the 2004 model year.

BMW's parts catalog lists the M56 only under US-specification cars; no other market's cars carry it. BMW's service documents tie the SULEV label to this engine, saying 'US cars with M56 engine only' are SULEV. It is a separate engine from the M54 it was derived from, which has its own guide.

Quick read

• Ownership position: Not established yet. We are still researching this engine.
• Reliability: Not established yet. We found no BMW recall or service bulletin written specifically for the M56.
• Cost to own: Not established yet. We are still researching this engine.
• Power potential: Not established yet. No BMW document we opened gives a tuning limit or factory output for the M56.
• Main watch item: Not established yet. We are still researching this engine.

M56 At a Glance

Question	Practical answer
Sold in US-market BMWs?	Yes, and only there. BMW's parts catalog lists the M56 only in US-specification E46 cars.
Cars	E46 325i sedan, 325i wagon and 325Ci coupe.
Factory output	Not established from a BMW document. Wikipedia gives 135 kW (184 PS), and the same page says performance matched the M54B25 car.
Engine oil	BMW's February 2017 oil chart (SI B11 01 15) lists 5W-30 LL01 or 0W-30 LL01FE for all BMW gasoline engines of model year 2011 and older.
Oil capacity	BMW's fluid data lists 6.5 liters for the US M56 cars.
Oil consumption allowance	BMW's SI B11 03 13 says all BMW engines except Motorsport engines can use up to 1 quart of oil per 750 miles at any time.
Recalls tied to M56 cars	Not established yet. We did not find an engine-specific NHTSA recall for the M56.
Reliability profile	Not established yet. We are still researching this engine.
Typical annual planning budget	Not established yet. We are still researching this engine.
Before buying	Confirm the engine is an M56 and not an M54, then ask a BMW dealer to check your VIN for open recalls.

Where you find it

BMW's US-specification parts data lists the M56 in the cars below. The parts data ends in December 2019 and shows catalog build dates, which can start before US sales.

Chassis	US model, body and build dates (BMW parts catalog)
E46	325Ci coupe, built 9/2002-5/2006
E46	325i sedan, built 9/2002-12/2004
E46	325i wagon, built 9/2002-1/2005

Wikipedia dates M56 sales to the 2003 model year onward, and the parts catalog's M56 build dates start in 9/2002.

Technical Specifications

Specification	Detail
Designation	BMW's service documentation designates the engine M56B25.
Displacement	Not established from a BMW document. Wikipedia describes a 2.5 liter engine.
Output	Not established from a BMW document.
Emissions	SULEV on US cars with the M56.
Timing drive	BMW's parts catalog lists a timing chain (11 31 1 432 176) and chain tensioner (11 31 1 703 717) for the M56.
Engine oil	5W-30 LL01 or 0W-30 LL01FE (BMW February 2017 oil chart, model year 2011 and older).
Oil capacity	6.5 liters in BMW's fluid data.
Block	BMW's main bearing bolt table puts the M56 in one tightening group with the M54, the M52TU and the M52 with an aluminum engine block. We did not find a block statement written specifically for the M56.
Firing order	Not established yet. We are still researching this engine.

Factory Deep Dive

What BMW documents say about the M56

BMW's service documents list the M56 together with the M52TU and M54 in repair instructions that cover the radiator, crankshaft main bearings and other jobs. BMW's parts catalog lists the same coolant pump, thermostat housing, timing chain and oil filter parts for the M56 as for the M54 and M52TU.

SULEV radiator

BMW's radiator repair text says US cars with the M56 (SULEV) need a specific radiator, identified by its black color and a sticker.

What we could not establish

We found no BMW training module for the M56, so power, compression ratio, VANOS and engine management details are not established here.

Service Parts at a Glance

Part	BMW part number (current)	Note
Spark plug, High Power	12 12 0 037 607	Current; listed for M50, M52, M54 and M56 cars.
Ignition coil	12 13 8 616 153	Current; listed for M54 and M56 cars.
Coolant pump (mechanical)	11 51 7 509 985	Current; listed for M52TU, M54 and M56 cars.
Thermostat housing with thermostat	11 53 7 509 227	Current; listed for M52TU, M54 and M56 cars.
Oil filter element set	11 42 7 512 300	Current; listed for M52, M54 and M56 cars.
Air filter element	13 72 1 730 449	Current; also listed for M50, M52 and M54 cars.
Radiator (automatic, to 9/2005)	17 11 7 513 922	Current; listed for M56 cars with an automatic transmission built to 9/2005.
Radiator (automatic, from 9/2005)	17 11 7 548 432	Current; listed for the M56 325Ci coupe with an automatic built from 9/2005.
Timing chain	11 31 1 432 176	Current; also listed for M50, M52 and M54 cars.

A matching part number locates a part; it does not confirm that it fits a specific VIN.

Known Failure Points and Service Items

Recall information on this page was checked against NHTSA on October 1, 2026. Recalls are added and closed over time. Whether a specific car is covered is a VIN check with BMW or NHTSA. We found no recall or service bulletin written for the M56 alone, which is a limit of our search and not a clean bill of health.

01 Oil consumption and crankcase ventilation

BMW's oil consumption bulletin SI B11 03 13 says all BMW engines except Motorsport engines can use up to 1 quart of oil per 750 miles at any time. It lists maintenance, external leaks, overfilling, oil viscosity, engine speed and load, and a malfunctioning crankcase ventilation system among the causes to check before engine repairs.

Watch for oil use beyond that allowance, with an engine that is otherwise leak-free and correctly filled.

Reliability Verdict

Not established yet. We are still researching this engine.

Power Potential

Not established yet. We are still researching this engine.

Cost of Ownership

Not established yet. We are still researching this engine.

Common Questions

What BMW has the M56 engine?

BMW's US-specification parts data lists the M56 in the E46 325i sedan, 325i wagon and 325Ci coupe.

Was the M56 sold outside the US?

BMW's parts catalog lists the M56 only under US-specification cars, and Wikipedia says it was exclusive to the US market.

What is the difference between the M56 and the M54?

Wikipedia describes the M56 as a re-engineered M54B25 built to meet the SULEV standard, and BMW's service documents say US cars with the M56 are SULEV.

How much oil does an M56 take?

BMW's fluid data lists 6.5 liters for the US M56 cars.

What oil does an M56 use?

BMW's February 2017 oil chart says model year 2011 and older gasoline engines use 5W-30 LL01 or 0W-30 LL01FE.

Sources

• BMW SI B11 01 15 (February 2017), engine oil chart
• BMW SI B11 03 13, engine oil consumption
• Wikipedia, BMW M56 (basics only)
• BMW dealer repair and service documents referred to for the SULEV label, radiator and engine designation; these are BMW internal documents and are not hosted publicly.