The manual will specify the recommended oil weight (e.g., 5W-30, 10W-30, 15W-40) and the type (conventional, synthetic blend, or full synthetic). It might also specify API certifications (like SJ, SL, SM, etc.). Using the incorrect oil can damage your engine.
If you don't have the owner's manual, you can try:
* Finding a digital version online: Search for "1998 Ford E350 owner's manual" on a search engine. Ford's website might have it available for download.
* Checking the oil fill cap: Sometimes, the recommended oil type is printed on the oil fill cap.
* Looking at the sticker under the hood: There's often a sticker near the radiator or elsewhere under the hood that provides information on recommended fluids.
Do not guess. Using the wrong oil can lead to serious engine damage. Always consult your owner's manual or a qualified mechanic.
