Flush swing drive gear oil with kerosene?

I’m draining and refilling the swing drive gear oil on my Kobelco K909. Doesn’t look too bad bad there’s some sludge coming out at the end. I’ve read elsewhere that I can flush the final drives with kerosene, can I do the same on the swing drive? It takes almost 5 gallons of 80w90. If yes, how much kerosene to run through? I have plenty lying around. Thanks!