Can I use heating oil from an underground tank?

[Dr. Smasher]

I have an 05' CRD and my father has an in ground oil tank that has about 200 gallons of fuel in it that he wnats out. The tank is old and the fuel has been sitting in it for at least 8 years. Should I not use this at all or can it be filtered and treated so I can run it in my truck? Would I need to run a smaller micron fuel filter than stock? I have the pumping equipment that is hooked up to a 6 micron filter and water seperator, which I will be using to pump it out into a 55 gallon drum for treatment and storage. I am not sure how to deal with this and am looking for good advice and info. Thanks.