However, generally speaking, for a 1989 Jeep Wrangler, you'll likely want to use:
* SAE 10W-30 or 20W-40: These are common viscosities for older engines. The best choice will depend on your climate. 10W-30 is generally better for colder climates, while 20W-40 is better for hotter climates.
* API certified oil: Look for an oil that meets the API service classification recommended in your owner's manual. This will usually be something like "SF", "SG", or possibly even "SH" for older engines, but again, check your manual. Modern oils often exceed these older standards, so don't be concerned if you find something newer.
* Conventional or Synthetic: Conventional oil is generally less expensive, while synthetic oil offers better performance and longevity. Either is acceptable, depending on your budget and preferences. Many people use conventional oil in older engines successfully.
Before you change your oil, consult your owner's manual. It will specify the correct oil type and viscosity for your specific engine. Using the wrong oil can damage your engine.
