A small funnel sometimes helps to force feed the pump with a small hose attached. I made a pressure pre- lubricator from a Hudson pump up sprayer and cut the metal spray rod end and threaded it to accept a busing for a 1/4" pipe thread. added oil pumped it up and shot the pressure to it while the engine was being spun with the plugs out. This was a have too situation , My shop was two days out and I had a friend who bought a re-con engine and it would not oil. The new sprayer was about 10.00 to 15.00, a heck of a lot cheaper than ruining an engine, and may be the sprayer could be used again if you do much engine work. The sprayer didn't react to the oil, we used to use them to spray diesel without a problem , I would use a light oil to pressure prime, only if you go the pump up sprayer route .