I have old Karosene can with a film of sludge in the bottom,how do I clean this out

This older white/clear 5 gal can is labled Karosene and as the remainder of unused karo evaporated it left a brown residue film. Can I refill this can? Clean it with something then refil or just buy a new can? my funds are limited and I don't want this can wasted if possible.