Model: Lancer Evolution Evo 4 through 9 & Evolution 10
Engine: 4G63 / 4B11
One of the seldom-weak points of the 4G63 / 4B11 is the rise in oil temperature. It is seen more often in circuit driving.
The EVO uses a thermo switch that will work when the temperature gets around 85°C (approx 185°F).
Yet when the oil temp is low, it will restrict the oil flow to the oil cooler constantly regardless of the temperature.
Still it is easy to revert back to the OEM switch for winter use to prevent over cooling.