I have an oil furnace and someone gave me oil and it might have sludge and water in it.

Cat

I have an oil furnace and someone gave me about 150 gallons of oil and it might have sludge and water in it what additive can I use to remove that without messing up my tank and the furnace.

EdTheHeaterMan

Where is the oil now?

If you already put it in your tank then this advice is too late.

Do not put that oil in your oil tank.
Leave it in the container that it came in.
Let it settle for a week or two in that container(s) so the sludge goes to the bottom
Run a temporary fuel line from about 4" * from the bottom of the container out of the top then down to your burner
Prime your burner and operate from that container until it is empty.
Discard any fuel that is remaining at the bottom of that container
When finished using that oil, reconnect to your tank.

This way you will not contaminate your tank and end up with years of service calls from that FREE oil you just saved money on. What does a service call cost in your area? (Rhetorical question. Don't answer that. we don't discuss Price here)

* Assumes there is less than 2" of tank bottom deposits. Adjust distance from bottom based on actual conditions.

Grallert

If it's already in the tank, check the filter for water and or sludge. There's not a lot you can do to get it out short of repeatedly replacing the filter or pumping it out of the tank and following the instructions above.

EBEBRATT-Ed

The oil may be ok or not. As a minimum I would buy some oil treatment and put it in the tank, I would buy some spare oil filters and have them on hand.