You MUST check your owner's manual to confirm which engine is in your specific Jeep. The manual will also specify the recommended oil viscosity and type (e.g., conventional, synthetic blend, or full synthetic).
However, as a general guideline:
* For both the 4.0L and 2.5L engines, a common recommendation is 10W-30. This is a good all-around viscosity for most climates.
* Oil type: Conventional oil was standard back then, but a synthetic blend or full synthetic will offer better protection and longer life. Using a higher quality oil than the minimum requirement is generally a good idea, especially for an older vehicle.
* Oil certification: Look for an oil that meets or exceeds the API (American Petroleum Institute) specifications listed in your owner's manual. This usually includes a designation like "SF," "SG," "SH," or something more recent, depending on the age of the manual. You will also want an oil that meets the proper ILSAC (International Lubricant Standardization and Approval Committee) standards.
Before you buy oil, always double check your owner's manual for the specific recommendations for your Jeep's engine. Ignoring this could lead to engine damage.
