I 3d print a lot for both my day job and side work, and I wouldn't use a printed part as the oil drive coupler. I think if printed correctly out of the correct material there would be no issue but there are far too many people that can't print anything but PLA and do not match their materials to the needs of their functional prints. First 787 I ever pulled apart I was actually a little surprised a crtitical failure mode piece like that was some sort of nylon or poly or whatever it is and not machined aluminum.