Cadillac CTS - Manual (Page 383)

Rear Axle
When to Check Lubricant
It is not necessary to regularly check rear axle
fluid unless you suspect there is a leak or you hear
an unusual noise. A fluid loss could indicate a
problem. Have it inspected and repaired.
How to Check Lubricant
To get an accurate reading, the vehicle should be
on a level surface.
If the level is below the bottom of the filler plug
hole, located on the rear axle, you’ll need to add
some lubricant. Add enough lubricant to raise
the level to the bottom of the filler plug hole.
What to Use
Refer to the Maintenance Schedule to determine
what kind of lubricant to use. See Recommended
Fluids and Lubricants on page 474.
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