Search "Helm" for a publisher for most automotive owners manuals.

Depending on the age of the vehicle auto recyclers often have manuals taken from the cars that they dissassemble.

As far as the oil that it takes, what kind of car, year, and engine? I could easily help you there, in fact it might be written on the underhood engine decal, or maybe even the oil fill cap (if it's the original)

Ebay!!!

I got mine on e-bay. It's a computer version in an Adobe format, just like an actual hardcopy, but on my computer. Cost me $3.

Some manufacturers offer free pdf copies of their owner's manuals on their websites.
I like the getting a copy from the junkyard idea, too.
Good Luck
Ralph