Volvo D11F Operator's Manual And Maintenance Instructions page 96

92 Maintenance and Service
Front Wheel Hubs
Failure to keep wheel bearings properly adjusted and lubricated may result
in accelerated tire wear, poor handling and, in extreme cases, wheel
separation from the hub or from the spindle resulting in loss of vehicle
control and serious personal injury or death.
The front wheel hubs can be filled with one of several types of oil. Motor oil
should be SAE 30 or 15W40. The oil can be either petroleum based or
synthetic (synthetic should not be used for the Volvo axle). Axle oil, API
GL-5, SAE 75W-90, can also be used. There are no set change intervals for
hub lubrication. The only requirement is that if the hub is opened, the
lubricant must be changed.