The N55 engine is no stranger to oil cooling problems, that’s why we recommend installing the MSL Oil Thermostat. The standard oil thermostat will reach around 120 degrees Celsius with a normal driving style. The MSL Oil Thermostat will open at a lower temperature than the standard oil thermostat (at 85 degrees Celsius) and will keep the temperature stable between 95 and 105 degrees Celsius, depending on the car model. Installing the MSL thermostat ensures a cooler oil temperature which will result in more stable performance, but above all this improves the reliability of the engine. It is recommended to install the thermostat, especially for cars that are tuned. The Thermostat is plug-and-play and made out of a solid block of high-grade aluminum at our own facility. It is equipped with a real thermostat, not an always open solution. The oil will still reach the operating temperature at the same time as a stock thermostat. The Oil Thermostat Installation kit (included in this price) prevents the Oil Thermostat from leaking and is highly recommended when installing the MSL Oil Thermostat. The kit includes 2 x O-ring for the oil hose and 1x rubber oil filter housing gasket. We advise to add it to your order. To fit models with N55 engine. E82/E88 135i, F20 / F21 M 135i, F22 / F23 M135i, E92 LCI / E90 LCI 335i, F30 / F31 335i, F32 / F33 / F36 435i, F34 335i.