How do I keep my diff fluid in my diff as opposed to seeping out the right side out-drive?

I filled it with a synthetic grease that seemed to work excellently the first few batteries but kept coming out of the right side out drive. After about four 5000Mah Lipo batteries I've taken it apart and found about the same amount left in it that the factory put in it. Everything is coated for sure... but it's not full like I left it.

Are there better than factory o-rings to replace the ones behind the sun gears?