The type of oil for a 1999 Ford Expedition depends on the engine it has. Ford Expeditions from that year could have a 4.6L V8 or a 5.4L V8.
You MUST check your owner's manual to be absolutely certain. The manual will specify the correct viscosity (like 5W-30 or 10W-30) and the type of oil (conventional, synthetic blend, or full synthetic).
However, a common recommendation for these engines is 5W-30 conventional, synthetic blend, or full synthetic oil. Using the weight recommended in your owner's manual is crucial for proper engine lubrication and longevity. Don't just rely on general advice; consult your owner's manual.
