2004 Jeep Grand Cherokee Owner's Manual - Page 231

STARTING AND OPERATING 231 NOTE: If you tow a trailer frequently, especially in hilly country or when the outdoor temperature is high, we recommend that you change the transmission fluid at 30,000 mile (48 000 km) intervals. RECREATIONAL TOWING (BEHIND MOTORHOME, ETC.) CAUTION! Internal damage to the transfer case will occur if a front or rear wheel lift is used when recreational towing. CAUTION! When pulling a heavy load or driving a fully loaded vehicle use a premium unleaded fuel to help prevent spark knock. If spark knock persists, lighten the load. Otherwise, engine piston damage may result. Other restrictions apply concerning trailer type, trailer frontal area and tongue weight. Carefully review the "Minimum Vehicle Requirements" chart in this section before towing a trailer. 5 NOTE: The transfer case must be in the N (Neutral) position, and the transmission must be in the P (Park) position for recreational towing. (Recreational towing is not available on Quadra-Trac I equipped vehicles.)