The Mitchell 1 Techline has heard of a very limited number of cases involving engine oil seals leaking after being displaced from their normal positions. As the engine heats and cools, condensation can accumulate in the PCV system, which, in extreme cold, can eventually turn to ice.
Upon closer inspection, technicians have reported finding accumulations of ice restricting or blocking airflow through the PCV system. When the engine’s PCV system cannot “breathe” properly, excessive crankcase pressure can build, resulting in oil seal displacement/leak.
Once the seal is displaced, the pressure buildup condition is gone. This situation can easily be overlooked if the vehicle is brought into the shop the night before inspection and/or repairs begin and allowed to “thaw out.” Once thawed, the blockage is gone and the PCV system returns to normal operation. This condition has been found to occur only on turbocharged vehicles operating in extreme cold temperatures.
Courtesy of Mitchell 1.