The oil in my 64 chevelle SS, has been leaking. I notice it when I leave the car parked in the same place overnight. It is leaking from the back between the 2 rear tires. The thick black stuff that I see ( I put a white paper under the car) is about the size of a nickel and then all around it will be a grease stain. I check the fluids all the time and it is the oil I have to keep putting in. I only know very minor things about cars. Please help.
Thanks.

Between the two rear tires? That would be the lube oil inside the rear end. It could be leaking pinion seal, or something as simple as loose housing cover bolts. Check the bolts to see if they're loose. If they're good and snug, you'll need to take the car in to have the pinion seal changed. It's not a job for someone lacking in experience unless you can find someone experienced to help. Are you in the Dallas/Fort Worth area?