The oiler for a jeep is a classic shaped oil can with the flexible base to "pop" out a drop or two of motor oil for general lube jobs.
I now have two of them, both by the Gem Manufacturing Co, Pittsburgh PA.

Gem Oilers 1

The left hand oiler has a 4 inch base and stands 6 & 3/4 inches tall, its marked "GEM MFG CO PITTSBURGH PA"

The right hand one has a 4 & 5/16 base and stands 6 & 1/2 inches tall, this one is marked "GEM MFG. CO. PITTSBURGH"

Gem Oiler 4 inchGem Oiler 4+5 sixteenths

The larger oiler has a much deeper stamping than the smaller one with a shorter spout, the bases are identical in manufacture.

Gem Oilers 2

Both oilers are considered "correct" for a jeep and they both fit nicely into the oil can bracket. Rumour has it the 4 inch base is a bit rarer.

More photos at:

http://www.surfacezero.com/g503/showgallery.php?cat=500&ppuser=498

For all your Jeep and Dodge needs:

http://dallasautoparts.com/index.htm