One problem related to engine burning oil has been reported for the 1998 Ford Expedition. The most recently reported issues are listed below.
Engine failure. In my research of the type of engine in my vehicle, a 4. 6l made in the romeo plant, have found that there has been numerous people that had their motors fail(blown). I have a Ford Expedition 1998 with a 4. 6l engine and the 8th digit of the VIN # being a w for romeo plant. When I called in excess of 20+ auto salvage yards, I had gotten the same response. That particular engine from that particular plant was a problem. I was also told 1997 was the same occurrence. Unfortunately, I owe almost $7000. 00 on this vehicle that I now can not drive with out replacing or rebuilding the engine, which will be more than a couple thousand. I have been told by these many salvage yards and my local Ford dealer the problem occurs when antifreeze makes its way into the oil and burns out the main bearings.