42
Section 6
Lubrication
The use of incorrect lubricants or inadequate
additives generally is the major cause of
differential failure. The lube oil specified for
differentials must possess extreme pressure (EP)
characteristics, API-GL-5 service classification of
the American Petroleum Institute. This type of oil,
better known as hypoid oil, possesses a
lubricating film that has the capability of
supporting the load pressure of heavy loads,
which makes it adequate for hypoid gears,
whose conditions are quite severe.
Viscosity
In general, the high grade of viscosity of the
monoviscous oil is adequate for higher ambient
temperatures. Besides prolonging the service life
of the gears, opting for a multiviscous oil will
satisfy all the temperature conditions found. The
following table represents the selection of oil
viscosity.
Inspection and Recommendations
Every 1,250 miles (2000 km) check if the oil level is
correct. Drain the oil when it is still hot. This
allows the lubricant to run freer and faster,
reducing the time needed to completely drain the
oil from the differential. Top off or refill until the
lubricant drips lightly from the lower edge of the
oil fill and level check hole.
The axle must not be washed internally with any
type of solvent (kerosene, gasoline, diesel oil,
etc.). After each oil change and before returning
the vehicle to normal operation, drive it, limiting
the speed to 25 mph (40 km/h) for 5 or 10 minutes
or 1-2 miles (2-3 kilometers) to ensure that all the
lines are properly full of lubricating oil. If the
differential is a spare unit and it is not likely that it
will be put back into service in the near future, all
the bearings and gears should be covered with a
good film of anticorrosive oil. In this event, the
differential must be stored in a closed box until it
is used to protect it from dust and other
impurities.
Oil Change Periods
New or Reconditioned Units
For the initial period (breaking in), the differential
oil change must be done between 1,250 and
3,100 miles (2000 and 5000 km). This initial oil
change is recommended to ensure that the
metallic particles that form to a greater degree
during this phase are removed.
Post-Breaking in Period
On vehicles that operate on highway with
workloads under their maximum permitted
capacity, the oil change can be performed every
100,000 miles (160 000 kilometers) or once a year,
whichever comes first.
On vehicles that operate on the highway or
off-road doing heavy-duty jobs, hauling the
heaviest loads permitted, the oil change should be
pe0rformed at intervals of 25,000-31,000 miles
(40 000-50 000 km) or every 6 months, whichever
comes first.
Magnetic Plug
Meritor recommends the use of magnetic plugs
for the axle oil draining port.
NOTE:
The magnetic plug loses its efficiency very
soon when it accumulates too many metallic
particles and should be cleaned before this
happens. After removal and cleaning, the plug can
be reused. It is recommended that this procedure
be practiced repeatedly between oil change
periods.
Figure 6.1
Meritor Lubricant
Specification
Description
Cross Reference
Minimum Outside
Temperature
Maximum Outside
Temperature
0-76-A
Hypoid Gear Oil
GL-5, S.A.E. 85W/140
+10°F (–12.2°C)
- - -**
0-76-B
Hypoid Gear Oil
GL-5, S.A.E. 80W/140
–15°F (–26.1°C)
- - -**
0-76-D
Hypoid Gear Oil
GL-5, S.A.E. 80W/90
–15°F (–26.1°C)
- - -**
0-76-E
Hypoid Gear Oil
GL-5, S.A.E. 75W/90
–40°F (–40°C)
- - -**
0-76-J
Hypoid Gear Oil
GL-5, S.A.E. 75W
–40°F (–40°C)
+35°F (+1.6°C)
0-76-L
Hypoid Gear Oil
GL-5, S.A.E. 75W/140
–40°F (–40°C)
- - -**
** There is no upper limit on these outside temperatures, but the axle sump temperature
must never 250°F (121°C).