N55 Servicing & Maintenance
Please take this advice as general in nature and choose what best works for you and your situation.
Performance Recommended Service Intervals
| Item | Interval |
|---|---|
| Engine Oil | 10,000 KM or 5,000 KM if using Ethanol Fuels regularly |
| Transmission (Auto) Oil | 80,000 KM |
| Transmission (Manual) Oil | 50,000 KM |
| Transmission (DCT - S55) | 50,000 KM |
| Differential Fluid | 50,000 KM |
| Transfer Case Fluid (xDrive) | 50,000 KM |
| Spark Plugs | OEM Gap 50,000 KM, 0.022inch Gap 25,000 KM |
| Coil Packs | 80,000 KM |
| Injectors | 120,000 KM |
| Coolant | 85,000 KM |
| Brake Fluid | 50,000 KM |
| Brake Pads | 50,000 KM or When Indicator Lamp Is Active |
| Intake Filter | 50,000 KM |
| Cabin Filter | 30,000 KM |
| Accessories Belt | 100,000 KM |
Preventative Maintenance & Common Failure Points
Valve Cover & Gasket
The N55 valve cover is made of plastic and is prone to cracking. The gasket also deteriorates over time, causing oil leaks. Replace the entire valve cover assembly if cracked.
Oil Filter Housing Gasket
A common source of oil leaks on the N55. The gasket deteriorates over time and should be replaced preventatively around 80,000 KM.
Charge Pipe
The stock plastic charge pipe is prone to cracking under boost, especially when tuned. Upgrade to an aluminium charge pipe is highly recommended.
VANOS Solenoids
VANOS solenoids can fail over time causing rough idle and performance issues. Regular oil changes help extend their life.
Water Pump & Thermostat
The electric water pump and thermostat are common failure items. Preventative replacement around 100,000 KM is recommended.
Wastegate Rattle (N55 PWG)
E-Series N55 models with pneumatic wastegates are known for wastegate rattle at idle. This is largely cosmetic but can be addressed with upgraded wastegate actuators.
High Pressure Fuel Pump (HPFP)
Early N55 models use the same/similar HPFP as the N54, which was known for reliability issues. Later N55 models use a more reliable vacuum pump driven Bosch HPFP with improved durability. Both variants can struggle when running E85 or high power levels without upgrading.
Carbon Buildup
Direct injection engines are prone to carbon buildup on intake valves. Install a catch can and consider periodic walnut blasting to maintain performance.
Injector Seal Leaks
Injector seals can deteriorate over time causing fuel smell and potential misfires. Replace seals during injector service.
Recommended Engine Oils
Understanding Oil Weight Classifications
Multi-grade oils are rated with two numbers separated by a W (e.g. 5W-40). The W stands for Winter and refers to the oil's viscosity at cold temperatures.
- •First number (e.g. 0W, 5W, 10W) — The oil's cold temperature viscosity grade. Lower numbers mean the oil is thinner and flows more easily when cold. A 0W oil has lower viscosity at cold temperatures than a 10W, meaning it circulates faster through the engine on a cold morning.
- •Second number (e.g. 30, 40, 60) — The oil's viscosity at operating temperature (100°C). Higher numbers mean a thicker oil film at temperature, providing greater protection under load and at higher temperatures.
Example: A 5W-40 has the cold viscosity of a 5-weight oil, allowing it to flow and circulate quickly when cold, while maintaining the thickness of a 40-weight oil at 100°C. A 0W-40 would have even lower cold viscosity but the same oil film thickness at operating temperature.
BMW LL (Long Life) Oil Ratings
- LL-98: Older gasoline engines (1998)
- LL-01: High temp stability for gasoline (2001)
- LL-04: Gasoline & diesel with DPF (2004)
- LL-01 FE: Fuel economy variant of LL-01, uses lower viscosity for reduced friction
- LL-12/14/17 FE+: Fuel economy focused for newer engines
N55 engines are compatible with LL-01 rated oils.
The oil weights below may not be 100% what you need if you have had an engine rebuild. Refer to your engine builder on what oil weight you should run based on your bearing clearances.
For Extreme Racing Applications
| Weight | Brand | Rating |
|---|---|---|
| 10W-60 | Shell Helix Ultra Racing | A3/B4, BMW M Approved |
| 10W-60 | Castrol EDGE Supercar | A3/B4, BMW M Approved |
| 10W-60 | BMW M TwinPower Turbo | A3/B4, LL-01 |
| 10W-40 | Motul 300V Competition | A3/B4, Ester Core |
| 15W-50 | Red Line Racing Oil | A3/B4 |
| 10W-40 | Penrite 10 Tenths Racing 10 | A3/B4, LL-98 |
For Most Climates
| Weight | Brand | Rating |
|---|---|---|
| 5W-40 | Castrol EDGE | A3/B4, LL-01 |
| 5W-40 | LIQUI MOLY Pro-Engine M900 | A3/B4, LL-01 |
| 5W-40 | Mobil Super Synthetic Formula B | A3/B4, LL-01 |
| 5W-40 | MOTUL 8100 X-CESS GEN2 | A3/B4, LL-01 |
| 5W-40 | Pennzoil Platinum Euro | A3/B4, LL-01 |
| 5W-40 | Shell Helix Ultra | A3/B4, LL-01 |
| 5W-40 | Penrite HPR 5 | A3/B4, LL-01 |
For Very Cold Climates
| Weight | Brand | Rating |
|---|---|---|
| 0W-40 | Castrol Edge | A3/B4, LL-01 |
| 0W-40 | Mobil 1 FS | A3/B4, LL-01 |