A turbocharger bearing housing defines a bore in which the turbocharger shaft is mounted for rotation in journal bearings. Lubricating oil is delivered to the journal bearings and a residue is retained in reservoirs in which the journal bearings are located. Two fluid retaining members are disposed around the shaft, each forming a wall of the reservoir and being sealed to the bearing housing. The lubricating fluid reservoir is provided between the fluid retaining members to a depth that at least partially immerses the journal bearings even when the oil supply is interrupted. This ensures that there is sufficient oil to lubricate the bearings at engine start-up, thereby reducing the risk of wear.