Chevrolet 2007 TrailBlazer Owner's Manua page 439

How to Check Lubricant
To get an accurate reading, the vehicle should be
on a level surface.
The proper level is from 0 to 3/8 inch (0 to 10 mm)
below the bottom of the filler plug hole, located
on the rear axle.
For vehicles equipped with the SS package,
the proper level is from 0.6 inch to 1.6 inches
(15 mm to 40 mm) below the bottom of the
filler plug hole, located on the rear axle.
Add only enough fluid to reach the proper level.
What to Use
To determine what kind of lubricant to use, see
Recommended Fluids and Lubricants on page 529.
For vehicles equipped with the SS package,
to add lubricant when the level is low, use
SAE 75W–90 Synthetic Axle Lubricant
(GM Part No. U.S. 12378261, in Canada
10953455) meeting GM Specification 9986115.
To completely refill after draining, add 5.5 ounces
(163 ml) of Limited-Slip Axle Lubricant Additive (GM
Part No. U.S. 1052358, in Canada 992694). Then
fill to the bottom of the filler plug hole with the
Synthetic Gear Lubricant.
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