You’d have to pump enough in there to force it back there. If you have a flexible hose on the end of a grease gun, you could do it that way.
But – if you’re not comfortable with that, the only other alternative is to remove the propeller and rear cap, and fill the gear cavity in directly.
Is it a standard prop, or variable pitch?
Best,
PM T2
He's livin' in his own private Idaho..... I hope to go out quietly in my sleep, like my grand-dad did..... and not screaming, like the passengers in his car...