Rear Axle

Vehicle Care / Vehicle Checks / Rear Axle

When to Check Lubricant

It is not necessary to regularly check rear axle fluid unless a leak is suspected or an unusual noise is heard. A fluid loss could indicate a problem. Have it inspected and repaired.

All axle assemblies are filled by volume of fluid during production.

They are not filled to reach a certain level. When checking the fluid level on any axle, variations in the readings can be caused by factory fill differences between the minimum and the maximum fluid volume.

Also, if a vehicle has just been driven before checking the fluid level, it may appear lower than normal because fluid has traveled out along the axle tubes and has not drained back to the sump area.

Therefore, a reading taken five minutes after the vehicle has been driven will appear to have a lower fluid level than a vehicle that has been stationary for an hour or two. Remember that the rear axle assembly must be supported to get a true reading.

How to Check Lubricant

2500HD with 6.0 L

All Other Series and Engines

To get an accurate reading, the vehicle should be on a level surface.

• For all 4.3 L, 4.8 L and 5.3 L 1500 Series applications, the proper level is 1.0mm to 19.0mm (0.04 in to 0.7 in) below the bottom of the fill hole, located on the rear axle. Add only enough fluid to reach the proper level.

• For all 6.0 L and 6.2 L 1500 Series applications, the proper level is from 15mm to 40mm (0.6 in to 1.6 in) below the bottom of the fill plug hole, located on the rear axle. Add only enough fluid to reach the proper level.

• For all 6.0 L 2500HD Series applications, the proper level is from 0mm to 13mm (0 to 0.5 in) below the bottom of the fill plug hole, located on the rear axle.

Add only enough fluid to reach the proper level.

• For all 6.6 L Duramax Diesel 2500HD Series applications and all 3500 Series applications, the proper level is from 17mm to 21mm (0.6 in to 0.8 in) below the bottom of the fill plug hole, located on the rear axle. Add only enough fluid to reach the proper level.

What to Use

Refer to Recommended Fluids and Lubricants on page 11‑12 to determine what kind of lubricant to use.