Detroit™ Model 4 and Model 6

Park the vehicle on a level surface, shut down the engine, and set the parking brake. Chock the tires.

Clean the fill plug and the area around it. In the axle housing rear cover, remove the plug from the oil fill hole. See Fig..

Front View

Rear View

Axle Breather

Breather Hose

Temperature Sensor Port

Oil Fill Plug

Fig. 1, Detroit Model 4 and Model 6 Tandem Axle (forward axle shown)

Place a drain pan under the rear axle drain plug. Drain the oil when it is warm. At this temperature, the oil will run more freely and ensure that the axle is flushed.

Clean the fill and drain plugs. Change them if necessary.

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.
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.
After the first oil is changed, inspect the drain plug each time for large quantities of metal particles.
After cleaning, install the drain plug(s) and tighten 30 lbf·ft (41 N·m).

Fill the axle with the recommended lubricant. See Table. for recommended drive axle lubricants and Table. for lubricant capacities.

Note: Some Detroit axles have a small tapped and plugged hole near and below the housing oil fill hole. This smaller hole is for a lubricant temperature indicator only, and should not be used as a fill or level hole.

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..

Important: Lubricant used in Detroit rear axles must meet Mercedes-Benz specification 235.8/Detroit Fluids Specification (DFS) 93K219.01. Mobil Delvac 1 Gear Oil 75W-90 meets this specification.

Note: Detroit rear axles do not require the use of friction modifiers.

Install and tighten the fill plug 30 lbf·ft (41 N·m).

Table 1, Detroit Drive Axle Lubricant, Model 4 and Model 6

Lubricant	Type	Ambient Temperature
Mobil Delvac 1 Gear Oil 75W-90	Synthetic	–40°F (–40°C) and up ¹

There is no upper limit on the ambient temperature.

Table 1, Detroit Drive Axle Lubricant, Model 4 and Model 6

Table 2, Detroit Rear Axle Lubricant Capacity, Model 4 and Model 6 (Hubs Full)

Axle	Oil Capacity: Quarts (liters)
Forward-Rear, Model 4	14.3 (13.5) ¹
Single and Rearmost Tandem, Model 4	10.6 (10.0)

Axle

Oil Capacity:

Quarts (liters)

Forward-Rear, Model 4

14.3 (13.5) ¹

Single and Rearmost Tandem, Model 4

10.6 (10.0)

These values assume the wheel ends are properly lubricated. Actual oil capacity might vary slightly depending on gear ratio.

Table 2, Detroit Rear Axle Lubricant Capacity, Model 4 and Model 6 (Hubs Full)

Correct (lube level at bottom of fill hole)

Incorrect (lube level below fill hole)

New Cascadia Maintenance Manual

Fig. 1, Detroit Model 4 and Model 6 Tandem Axle (forward axle shown)

Table 1, Detroit Drive Axle Lubricant, Model 4 and Model 6

Table 1, Detroit Drive Axle Lubricant, Model 4 and Model 6

Table 2, Detroit Rear Axle Lubricant Capacity, Model 4 and Model 6 (Hubs Full)

Table 2, Detroit Rear Axle Lubricant Capacity, Model 4 and Model 6 (Hubs Full)

Fig. 2, Axle Lubricant Level Inspection