Join Date: Jun 2006
Location: Eastern ON Canada
Car: 07 OBW 2.5i D-4AT
Feedback Score: 5 reviews
That sure looks like grease, and not power steering or automatic transmission fluid, which would be runny (i,e. liquid and not a paste). As far as I know, the only place where there's grease like that is in the drive axle CVs.
The axle boot appears clean in the first photo except at the top of the third ridge (counting from right to left) where there appears to be a darker area. Have you actually checked it all around for a crack in one of the folds? It might be only a partial break, rather than all the way around.
At the bottom center of the first photo there appears to be a more-or-less vertical line of grease on the cross-member as well as dots of grease on the engine around the front differential dipstick. This suggests that the grease was being flung out from somewhere, and the only centrifugal force source in that area is the axle. I think you could almost look at the line of grease on the cross member and find the area on the boot that corresponds.