Mosselman N55 Oil Thermostat 85°C for BMW M135i, M235i, 335i, 435i and M2 F Series
Lower your BMW N55 oil temperatures, protect your engine and unlock consistent, reliable performance with the Mosselman N55 Oil Thermostat 85°C. This is the proven oil temperature control upgrade for BMW M135i, M235i, 335i, 435i and M2 owners who drive hard on the road or track and want a simple, plug-and-play solution that actually works.
Stock N55 thermostats typically allow oil temps to climb to around 120°C under normal driving. The Mosselman thermostat opens earlier at 85°C and maintains a far more stable operating range of roughly 95 to 105°C depending on vehicle, giving you cooler oil, more consistent power and improved engine longevity. It is a genuine thermostat unit, not an always-open workaround, so your BMW still reaches operating temperature correctly in all climates.
We run this on our own N55 cars and it is a customer favourite for keeping oil temps under control on spirited drives and track days. If your N55 is tuned or driven hard, this is a must-have reliability upgrade.
Key features
- Opens at 85°C for earlier cooling and stronger temperature control
- Typically 20°C lower oil temps than stock, helping protect bearings and turbo
- Real thermostat design for correct warm-up and year-round drivability
- Billet high-grade aluminium housing for strength and durability
- Direct-fit, plug-and-play installation
- Approx. 30 minute install time for experienced technicians
Why upgrade your N55 oil thermostat
- Improved reliability and reduced heat soak during fast road and track use
- More stable performance with consistent oil pressure and viscosity
- Highly recommended for tuned and remapped N55 engines
Compatibility
- BMW M135i F20/F21 N55
- BMW M235i F22 N55
- BMW M2 F87 N55
- BMW 335i F30/F31 N55
- BMW 335i GT F34 N55
- BMW 435i F32/F33 N55
- BMW 435i Gran Coupe F36 N55
Note: For E-Series 135i and 335i with the N55 engine you will need the N54 Oil Thermostat.
Recommended parts
- MSL Installation Kit – prevents leaks during refit. Includes 2 x oil hose O-rings and 1 x rubber oil filter housing gasket.
- MSL Titanium GR5 Hex-Race Bolt Set
Installation and fitting
- We strongly recommend fitting a fresh oil and filter at the same time as the thermostat install.
- For professional installation, book with Nforcd in Warwickshire. Request a fitting quote: sales@nforcd.com
Compatibility check
Before dispatch we can confirm fitment to your vehicle. Provide your UK registration number or the last 7 digits of your VIN at checkout and we will verify compatibility.
Part number
OTN55.T85
Manufactured by
Mosselman
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