Recommended Lubricant - Hummer H1 Service Manual

5-150 Transmission/Transfer Case
TRANSFER CASE OIL COOLER
The NP 242 used in Hummer vehicles is equipped with an in-
ternal oil cooler (Figure 5-67).
The cooler is mounted within the front case and secured by
nuts and washers. O-rings are used to seal the cooler inlet/out-
let tubes.
The cooler is interconnected to the transmission oil cooler cir-
cuit. However, transmission and transfer case oil are not inter-
mixed. In operation, oil from the transmission cooler flows
through the transfer case cooler. Heat from the transfer case oil
is transmitted to the transmission oil which is then conveyed to
the transmission cooler.
TRANSFER CASE INTERNAL OIL COOLER
O-RING
Figure 5-67: Oil Cooler Location
4-1-00
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SUPPORT
BRACKET
FRONT CASE
TRANSFER CASE IDENTIFICATION
An identification tag is attached to the rear case of each NP 242
transfer case (Figure 5-68). The tag provides the model num-
ber, assembly number, serial number, and low range ratio.
The serial number also represents the date of build. For exam-
ple, a serial number of 10-10-99 would represent a build date
of October 10, 1999.
Figure 5-68: Transfer Case I.D. Tag Information

RECOMMENDED LUBRICANT

Dexron III is the recommended lubricant for the NP 242. Use it
for topping off the fluid level and as replacement fluid for fluid
changes, or after overhaul. Dexron IIE can also be used for top-
ping off a low fluid level when Dexron III is not readily avail-
able.
Do not use friction modifiers or similar additives in the
NP 242. Use recommended lubricants only.
Transfer Case Fluid Level
Correct transfer case fluid level is to the lower edge of the fill
plug hole. Recommended fluid is Dexron III.
The vehicle must be on a level surface for an accurate fluid
level check. If the vehicle is raised on a hoist to check fluid
level, a drive-on style hoist is preferred. This type of hoist will
keep the vehicle level.
The fill plug is just above the drain plug in the rear case. Tight-
ening torque for the plug is 15-25 lb-ft (20-33 N•m).
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