Hi Mike. In general oil and resource will move by road and rail, just like supply, as long as it is possible to trace a valid supply path. You will need to ship oil and resource to the home islands from primary production centres. In my game I also keep an eye on Korea, HK, and SE Asia and as required ship oil to Haiphong, Saigon, Bangkok and Singapore and in Korea / China to Tientsin and Luda/Pyongyang.
SE Asia and Manchuria/China is a net producer of resources so I ship these out of Bangkok, Saigon and from wherever the surplus stock builds up in the Korean peninsula to home islands.
Within the home islands (excepting Hokkaido and Toyohara on Sakhalin which I keep supplied by convoy) oil and resource generally seems to move itself satisfactorily by road and rail, though I have shipped both oil and resource to Shikoku on occasion when local stocks get low. According to the manual (8.3) O&R will move between two adjacent base hexes even if they are separated by an ocean hex side so it should be possible for the O&R to get to Shikoku (and for that matter to Hokkaido) under its own steam but my experience is that this is not always the case.
My SOP is to unload O&R convoys as near to where it is needed as possible to minimise any losses in road and rail trans-shipment.
You will also need to keep Formosa and supplied with O&R by ship.
Nobody ever defended anything successfully, there is only attack and attack and attack some more.
George S. Patton