An encapsulation device suitable for encapsulating a transmission component of an engine system that comprises a housing member configured to encapsulate the transmission component and define an air gap in a volume between an outer surface of the transmission component and an inner surface of the encapsulation device in use. The housing member is configured to allow air flow through the air gap during operation of the engine system and to retain a heated air layer around the encapsulated transmission component following engine system shutdown in use. The air gap enables convective cooling of the transmission components during periods when the vehicle is driving and additionally allows heat dissipation to occur when the vehicle engine is switched off.