* Check your owner's manual: This is the single most important source of information. It will specify the correct viscosity (like 5W-30, 10W-30, etc.) and API certification (like SL, SM, SN, etc.) for your engine.
* Viscosity: Common viscosities for older engines like the one in your Ranger are 10W-30 and 5W-30. 5W-30 is generally preferred for better cold-weather performance, but 10W-30 is acceptable in many cases. Higher viscosities (like 20W-50) are generally not recommended for modern engines unless specifically stated in the manual, especially if the engine has higher mileage.
* API Certification: Look for an API certification on the oil bottle. Older certifications like SL or SM are still fine for older engines, but more recent certifications like SN, SN Plus, or SP are also acceptable and offer enhanced performance. Use whatever your owner's manual recommends.
* Oil Type: Unless your owner's manual specifically states otherwise, conventional oil is generally sufficient for a 1997 Ranger. Synthetic blends or full synthetics can offer some benefits (like extended drain intervals), but aren't strictly necessary.
In short: Don't guess. Find your owner's manual and follow its recommendations. This will ensure the longevity and optimal performance of your engine. If you don't have the manual, you can often find a digital version online through Ford's website or a reputable automotive parts website.
