[WE7X]

Steve,
It is really quite easy to make flat gaskets for things that are not particularly critical, such as the oil adapter.
Get a piece of flat gasket material from NAPA (or your choice of local suppliers).
Trim to close to the the needed size and tape it over the flange for which you wish to make a gasket. In this case, use the adapter assembly, preferably, clamped in a vice.
With the gasket material flat against the adapter, just lightly tap against the gasket material, around any openings, with a small hammer ( a ball-pien hammer works great). When done, you should be able to see an impression of the edges of the openings on the reverse side of the gasket material. Just cut out the unneeded parts, and you should have a very usable gasket.

This works very well for fuel pumps, thermostat housings. water outlets and various other relatively simple applications. With care, it can be done with more intricate designs.
Rod J
Issaquah, WA