Ford 1998 Windstar Owner's Manual page 275

What to Check When You Stop at a Service
Station
Engine Oil Recommendations
We recommend using Motorcraft oil or an equivalent oil
meeting Ford Specification WSS-M2C153-F and displaying the
American Petroleum Institute CERTIFICATION MARK on the
front of the container.
Use only engine oils displaying the American Petroleum
Institute CERTIFICATION MARK on the front of the container:
The API Certification Mark
Never use:
"Non-Detergent" oils
Oils labeled API SA, SB, SC, SD, SE, SF or SG
Additional engine oil additives, oil treatments or engine
treatments
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