How long does 4 inches of oil last in a 500 gallon oil tank?

How long does 4 inches of oil last in a 500 gallon oil tank?

It will last forever unless someone removes it...!

If you mean "How long will 4 Inches of oil last in the tank if you are using it to heat your house", that would be very difficult to answer as different furnaces will consume different amounts of oil, just like cars consume different amounts of fuel..

And, the colder it is outside, the more the furnace will run so It would consume the fuel faster.