Neil,
I have run into the same situation, the larger companies are usually inclined to have professional recyclers come pick up the oil,
Even pay for the service, So what your best bet is is find smaller outfits, Logging operations, small mechanic shops, Transmission shops, if they do not burn the oil themselves they are all to happy to get rid of it,
There are some transportation issues that you may wish to look into , for instance you need special permits to transport more then 100 gallons, in 1 container,
Its okay to have more then a 100 gallons if in separate containers, So 55 gallon drums,
or so I have heard,