Oil in the axle boots

[TimJ]

I have just been under the back of my 710M and noticed oil leaking. I tracked it down to the rear right hand axle boot. It appears that there is oil inside the boot that is leaking out through a small crack in the boot. The other side appears to have oil inside as well but isn't leaking because it is not cracked. Am I right in believing that there should be no oil inside the boots, that it is a diff removal and a very large job to fix the seals that are inside the the boots and that it is still a pretty big job just to replace the boots?

Also if I top up the oil in the diff and check it at the end will I be ok to go on the 6hr drive (each way) that I am supposed to be doing next weekend?

Thanks,

Tim.