Axle Lubricant Level Checking
Notice: Failure to keep the rear axle filled to the proper level with the recommended lubricant can result in rear axle damage.
- Park the vehicle on a level surface, shut down the engine, and set the parking brake. Chock the tires.
- If the vehicle has just been driven, allow a few minutes for the lubricant to settle.
- Clean the fill plug and the area surrounding the fill plug on the side of the axle carrier. Remove the plug. Check lubricant level when the axle is cold, or near room temperature. See Fig. and see Fig..
- Check that the lubricant is level with the bottom of the fill hole. See Fig.. If low, check for oil leaks, and correct as needed. Add oil to the level of the fill plug, using the lubricant, see Table. for Detroit axles or see Table. for Meritor axles.
- Install the oil fill plug and tighten it 30 lbf·ft (41 N·m) for Detroit axles or 35 lbf·ft (47 N·m) for Meritor axles.
- Check the axle housing breather. Make sure that it is open
and unclogged. If the breather is plugged or damaged, clean or replace
it as needed.
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Front View
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Rear View
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Breather Hose
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Axle Housing Breather
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Oil Drain Plug
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Oil Fill Plug
Fig. 1, Component Locations, Detroit Axles
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Axle Housing Breather
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Oil Fill Plug
Fig. 2, Component Locations, Meritor Axles
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Correct (lube level at bottom of fill hole)
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Incorrect (lube level below fill hole)
Fig. 3, Axle Lubricant Level Inspection
Table 1, Detroit Drive Axle Lubricants
Detroit Drive Axle Lubricants*
Important: Lubricant used in Detroit rear axles must meet Mercedes-Benz specification 235.20 (mineral) or 235.8 (synthetic). Mobil Delvac™ Gear Oil A 80W-90 and Mobilube™ HD-A Plus 80W-90 meet specification 235.20. Mobil Delvac 1 Gear Oil 75W-90 and Mobilube 1 SHC 75W-90 meet specification 235.8.
Type
Ambient Temperature
SAE Viscosity Grade
Mineral Oil
–15°F (–26.1°C) and up†
80W–90
Synthetic Oil
–40°F (–40°C) and up†
75W–90
Table 1, Detroit Drive Axle Lubricants
* Detroit rear axles do not require the use of friction modifiers.
† There is no upper limit on the ambient temperature.
Table 2, Drive Axle Recommended Lubricant, Meritor Axles
Drive Axle Recommended Lubricant, Meritor Axles
Recommended Lubricant Type
Ambient Temperature
Lubricant SAE Viscosity Grade
Hypoid Gear Oil API Service Classification GL–5
10°F (–12.2°C) and up*
85W–140
–15°F (–26.1°C) and up*
80W–90
–40°F (–40°C) and up*
75W–90
–40°F (–40°C) to 35°F (2°C)
75W
–40°F (–40°C) and up*
75W–140
Synthetic Gear Oil
–40°F (–40°C) and up*
75W–90
–40°F (–40°C) and up*
75W–140
Table 2, Drive Axle Recommended Lubricant, Meritor Axles
* There is no upper limit on the ambient temperature.
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Note: Some Meritor axles have a small tapped and plugged hole located below the housing oil fill hole. This smaller hole is for the lubricant temperature sensor only and must not be used as a fill or level hole.
Important: A lubricant level close enough to be seen or touched is not sufficient. It must be level with the bottom of the fill hole.
Important: Always check the axle breather whenever checking the lubricant level. Check the breather more frequently under adverse operating conditions.