Bottom side of engine.
For a V8 I would guess 4 quarts,usually the standard amount.
1-3-7-2-6-5-4-8
In a 1993 Ford E-250 : It must be a V8 cause the 6 cylinder is an inline ( straight ) engine that is 300 cubic inches / 4.9 liters
Ford says the 5.4 liter V8 engine is ( 330 cubic inches )
4 - 8 3 - 7 2 - 6 1 - 5 front ( Ford GASOLINE V8 engine )
Ford V8 4 - 8 3 - 7 2 - 6 1 - 5 front of Ford E-250
Front of vehicle 5 1 6 2 7 3 8 4 Firewall * for the GASOLINE V8 engines
On a Ford E-250 , 5.4 liter V8 engine : 4 - 8 3 - 7 2 - 6 1 - 5 front of vehicle
6 quarts w/ filter change * for the GASOLINE engines ( 4.2 liter V6 / 4.6 and 5.4 V8's / 6.8 V10 )
On a 2002 Ford E-250 : The GASOLINE engine choices were : The 4.2 liter V6 , 4.6 and 5.4 liter V8's , 6.8 liter V10 ( you could also get the 7.3 liter DIESEL which is a V8 )
According to the 2004 Ford E-250 Owner Guide : With engine oil filter change : The 4.6 liter gasoline V8 engine takes : ( 5.7 liters / 6.0 U.S. quarts of 5W-20 )