Sierra Classic 2500 4WD V8-8.1L (2007)
Fluid - Differential: Technical Service Bulletins
Drivetrain - Rear Axle Fluid Level May Appear Too Low
INFORMATION
Bulletin No.: 05-04-20-001A
Date: April 01, 2009
Subject:
Rear Axle Fluid Level May Appear To Be Lower Than Published Specification
Models:
2005-2009 Chevrolet Silverado 2500/3500 Series Pickups
2005-2009 GMC Sierra 2500/3500 Series Pickups
with Four-Wheel Drive (VIN K)
Supercede:
This bulletin is being revised to update model years and to reclassify the previous bulletin from Advanced Service Information to Information. Please
discard Corporate Bulletin Number 05-04-20-001 (Section 04 - Driveline/Axle).
On full-size 2500 and 3500 Series Four Wheel Drive (K Series) Chevrolet and GMC Pickups equipped with the 11.5" ring gear rear axle assembly, the
factory lubricant fill level may appear to be lower than the published specification. This unit can be identified by the location of the fill plug on the rear
axle housing cover, instead of on the front of the axle housing.
All axle assemblies are filled by volume of fluid during production. They are not filled to reach a certain level. On the 11.5" rear axle, the fill quantity is
3.0 Liters plus or minus 0.1 Liter (3.18 Quarts plus or minus 0.1 Quart). Testing has shown fluid level readings as low as 35 mm (1.4 in) below the
bottom of the fill plug opening are acceptable, even with the correct amount of fluid in the axle, compared to the currently published specification of
17-21 mm (0.6-0.8 in) below the fill plug opening, even when the correct amount of fluid was installed in the axle assembly during production.
It is NOT necessary to add axle fluid to the axle when the fluid level is at or above 35 mm (1.4 in) below the bottom of the fill plug.
When checking the fluid level on any rear axle, variations in the readings may be caused by factory fill differences between the minimum and 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 travelled 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.
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