NP242 Selec-Trac Transfer Case Fluid
NP242 holds about 1.5 quarts of ATF and is the full-time 4WD option with viscous coupler. Same plugs and procedure as NP231 but watch the slightly higher capacity.
The NP242 was the upmarket Selec-Trac case offering 2WD, Part-Time 4WD, Full-Time 4WD, N, and 4-Low. It contains a viscous coupling that lets you run on dry pavement in Full-Time mode. Capacity is approximately 1.5 quarts of ATF (specifically Mopar ATF+4 per recent service literature; Dexron is the historical fill). Fluid level is checked at the fill plug like the NP231. The NP242 weighs more, runs slightly noisier, and is rarer than the NP231 - many owners hunt them down for daily-driver builds because of the AWD capability. Skip changing fluid only if you know history; many used 242s have neglected fluid that has glazed the viscous coupling. The case is more sensitive to wrong fluid than the NP231 because of the VC - stick to ATF, not gear oil.
Why it works
- Full-time 4WD for daily driving
- Same maintenance as NP231
Trade-offs
- Viscous coupler can be damaged by wrong fluid
- Heavier
Tools required
- 8mm hex driver
- drain pan
- fluid pump
Parts
| Part | Vendor | Est. price |
|---|---|---|
| ATF+4 (2 qt) | any | ~$18 |
Sources
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Written and maintained by an AZ wheeler and driveway wrencher. How we source guides. Always cross-reference your factory service manual — modifications affect vehicle safety and warranty. Work at your own risk.