Filters for DAVCO Fuel Processors Place a drain pan under the Fuel Pro . Use the DAVCO collar wrench to loosen the vent cap. Remove the vent cap from the clear cover and set it aside. Dispose of the o-ring. With a drain pan under the Fuel Pro or Diesel Pro, open the drain valve and allow the fuel to drain below the filter element. (On the Fuel Pro 382, this level is about an inch below the collar. On the Fuel Pro 482 and the Diesel Pro, this level DAVCO Fuel Pro 382 The Fuel Pro 382 is a full function combination of diesel fuel filtration and water separation that will save you time, money and unnecessary down-time. The Fuel Pro 382 is recommended for heavy duty diesel engines with flow rates up to 180 gallon/hour.