Oil in Fuel

[Chamberpains]

If you're getting small amounts of oil in your davco then you should have huge amounts in your fuel tanks. Shine a flashlight in there and see if it's in your tanks.

Are you sure it's oil and not asphaltene? This is a common black substance that you will always see in your davco filter. it's a byproduct of the fuel system in the ISX. No way to get around it except for to filter it out. Have you had it sent off to be tested? they'll be able to tell you if it's algae, asphaltene, oil, or even coolant.