Without the owner's manual, a safe bet for a 1998 vehicle is likely to be 5W-30 conventional or synthetic blend motor oil. However, this is *not a guarantee*, and using the wrong oil could damage your engine. Always prioritize information found in your owner's manual.
If you don't have the owner's manual, you can often find a digital version online through the Ford website (Mercury was a Ford brand) by searching for your specific year, make, and model. You can also check with a local auto parts store; they may have access to this information.
