Meritor®

p4 mm 35.01.002

Important: On Meritor axles, the oil change interval for Schedule III vehicles is extended to 500,000 miles (800 000 km) for axles using synthetic lubricant with a pump and filter system.

On single drive axles so equipped, the traction equalizer may slip or stick. When this happens, the driver will hear intervals of shrill noises when the vehicle is driven at low speed or makes sharp turns. Use a "limited-slip friction modifier" to correct this slip/stick condition. Add 1.6 ounces (35 mL) of additive for each pint (0.5 L) of lube capacity.

For all GL-5 oils, add one of the following limited-slip friction modifiers:

  • Lubrizol No. 6178 (Lubrizol Corporation)

  • DSL-178 (Guardsman Products)

  • Equa-Torque No. 2411 (Sta-Lube Corporation)

  • Equa-Torque No. 2414 (Sta-Lube Corporation)

Important: These friction modifiers generally deteriorate faster than conventional extreme-pressure additives, so the lubricant change schedule must be shortened when using these additives. The traction equalizer additive (and recommended drive axle lubricant) must be changed at the Maintenance 2 (M2) interval, instead of the Maintenance 3 (M3) interval recommended in the Maintenance Operation Chart for axles that require only those lubricants recommended in Table..

  1. Park the vehicle on a level surface, shut down the engine, and set the parking brake. Chock the tires.
  2. Remove the axle carrier fill plug. Then remove the drain plug from the bottom of the housing. Completely drain the lubricant while the unit is warm, to allow the lubricant to drain faster.
    On tandem drive axles, it is also necessary to remove the plug at the bottom of the interaxle differential housing to drain that lubricant.
  3. If equipped with an oil pump, use a suitable filter strap wrench to remove the axle oil filter. See Fig.. Discard the old filter.

    Fig. 1, Meritor Axle Oil Filter Removal

    4. Note: There may be about one pint (0.5 L) of lubricant remaining in the filter. Be careful not to spill it when removing the filter.

  4. Using the recommended drive axle lubricant, coat the face of the gasket on the new oil filter, if it was replaced. Install the filter over the adapter, and tighten the filter one full turn after the gasket contacts the base; do not overtighten. See Table. for recommended lubricants.

    Table 1, Meritor Drive Axle Recommended Lubricant

    Recommended Lubricant Type

    Ambient Temperature

    Lubricant SAE Viscosity Grade

    Meritor Specification

    Synthetic Gear Oil

    –40°F (–40°C) and Up 1

    75W–90

    0–76–N

    –40°F (–40°C) and Up

    75W–140

    0–76–M
    1. There is no upper limit on these outside temperatures.

    Table 1, Meritor Drive Axle Recommended Lubricant

  5. Clean the fill and drain plugs. Change them if necessary.
    1. For magnetic plugs, use a piece of key stock or any other convenient steel slug to short the two magnetic poles and divert the magnetic field.
    2. Check the drain plug for metal particles every 100,000 miles (160 000 km). Clean away the collected material deposited on each pole. Magnets will rapidly lose their effectiveness as collected material bridges the gap between the two poles.
    3. Each time the oil is changed, replace any magnetic drain plug that does not meet the minimum pickup capacity.

      Note: Meritor recommends plugs with elements having a minimum pickup capacity of 1.5 pounds (0.7 kg) of low-carbon steel.
      1. After cleaning, install the drain plug(s) and tighten to 35 lbf·ft (47 N·m).
    4. Fill the axle with recommended lubricant. See Table. for drive axle lubricant capacities.

      Note: Some Meritor axles have a small tapped and plugged hole near and below the housing lubricant fill hole. This smaller hole is for a lubricant temperature indicator only, and should not be used as a fill or level hole.
        1. With the vehicle on a level surface, fill the axle through the oil fill hole. Lubricant should be level with the bottom of the oil fill hole. To check fluid level, see Fig..

          • Correct (lube level at bottom of fill hole)

          • Incorrect (lube level below fill hole)

          Fig. 2, Axle Lubricant Level Inspection

          Table 4, Meritor Drive Axle Lubricant Capacities

          Axle Model

          Capacity: 1 pt (L)

          Single Drive, Single Reduction2

          RS–21–160

          39.5 (18.7)

          RS–23–160

          39.5 (18.7)

          RS–23–161

          37.2 (17.6)

          RS–23–185

          47.3 (22.4)

          RS–25–160

          37.2 (17.6)

          Tandem Drive, Single Reduction

          RT–40–145, RT–40–145A, RT–40–145P

          Forward

          30.2 (14.3)

          Rear

          25.8 (12.2)

          RT–44–145, RT–44–145P

          Forward

          29.3 (13.9)

          Rear

          25.1 (11.9)

          RT–46–160, RT–46–160P

          Forward

          39.1 (18.5)

          Rear

          34.4 (16.3)
          1. Quantities listed are approximate. Fill axle until lubricant is level with bottom of fill hole with vehicle on level ground.
          2. See "Traction Equalizer Additives" in the text.

          Table 4, Meritor Drive Axle Lubricant Capacities

        2. Install and tighten the fill plug 35 lbf·ft (47 N·m).
      1. Whenever the interaxle differential housing has been drained, add an additional 2 pints (0.9 L) of the recommended lubricant directly into the interaxle differential housing.
      2. Remove the chocks, then drive the vehicle, unloaded, for 1 or 2 miles (2 or 3 km) at speeds not to exceed 25 mph (40 km/h), to thoroughly circulate lubricant throughout the carrier and housing assemblies.
      Note:
      Parent topic: All Axle models
      Document Number: 0000103613
      Manual Publication Date: 2024-05-15
      Topic Publication Date: 2025-04-05