engine oil weight / 1998 Lincoln Continental 4.6L

5w-20 oil is used in engines much newer then yours, do to changes in the way they are made. Todays engines are machined with very small tolerances, and many parts are not using bearings between parts any more. They need thinner oil to pump into these tight spaces. 5w-30 is still the correct oil for your car.

The dealership is correct: Ford Motor Company now recommends SAE 5W-20 viscosity grade for servicing most gasoline and flexible fueled vehicles. This is outlined in TSB 02-01-9