A Funnel with an extension works well. I got a metal one with a two foot bendy pipe.
Also, you can buy hand pumps. I got one from Amsoil and it works great on 5 gallon pails as well as gear oil containers.
Fail safe - Make a funnel out of a cereal box front. Use the tallest cereal box you have. It can be bent in many ways and rolled into a tube to fit into the filler hole.