* For both engines: The owner's manual likely recommends using SAE 5W-30 oil that meets the specifications of API SM or newer (SN, SP, etc.). This is a common and readily available motor oil.
* Check the Owner's Manual: The most accurate information is in your Jeep Liberty's owner's manual. It will specify the exact type and viscosity of oil recommended by Jeep for your specific engine. The manual will also specify the oil capacity for your engine.
Don't rely solely on online information. Always refer to your owner's manual for the definitive answer.