What size is the oil drain bolt on a 1998 ford truck?

The oil drain plug size for a 1998 Ford truck depends heavily on the engine. Ford used several different engines in their trucks that year. To know for sure, you must identify your engine. Look for an engine code (like a 4.6L, 4.2L, 5.4L, 7.3L Powerstroke, etc.) on a sticker under the hood or in your owner's manual.

Once you know the engine size, you can then find the correct drain plug size through a repair manual specific to your truck's year and engine or an online parts database like AutoZone, Advance Auto Parts, or RockAuto. Searching for "[Your Engine Size] 1998 Ford Truck Oil Drain Plug" will usually yield the correct information.