Dodge 2010 Ram Pickup 3500 Diesel - Manual (Page 82)

Engine Oil Viscosity (SAE Grade)
Use SAE 15W-40 engine oil that meets Chrysler Materials
Standard MS-10902 and the API CJ-4 engine oil category.
In ambient temperatures below 0°F (-18°C), SAE 5W-40
synthetic
engine oil that meets Chrysler Materials Stan-
dard MS-10902 and the API CJ-4 engine oil category is
required.
CAUTION!
Failure to use SAE 5W-40 synthetic engine oil in
ambient temperatures below 0°F (-18°C) could result
in severe engine damage.
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MAINTAINING YOUR VEHICLE 81