Volvo FM Handbook page 571

560 Maintenance
Gearbox Oil change volume, approx. litres
VT1706PT 35
VT1906PT 35
VT2006PT 35
VT2206PT 35
VT2506PT 35
Viscosity
Transmission oils fulfilling quality requirements of
both Dexron III and Allison C4 shall be used. This
automatically provides oils of the correct viscosity.
These oils must be used irrespective of ambient
temperatures.
Service intervals
• First filter change after 10,000 km or 4 weeks,
whichever occurs first. The oil level must be
checked after changing the filter. No oil change
shall be performed
• After the first filter change has been done, the oil
and filter shall be changed every 90 000 km or once
a year, whichever occurs first
• Under some gearbox operating conditions, shorter
change intervals may be necessary. Examples of
such are extreme heat and much use of the retarder
• The change interval must be halved for heavy
driving or frequent driving under hilly road
conditions
• All these types of gearboxes are equipped with a
ventilation filter, which ensures that air pressure
does not build up in the gearbox. The ventilation
filter must be kept clean and open, and therefore it
must normally be changed after 24 months. If the
gearbox is operating under very dusty and dirt
conditions, it will be necessary to reduce the
replacement intervals for the ventilation filter