Thanks for all the info.
To add to the discussion I just have to confess that the initial seepage of silicone out of the hub was definitely due to too much silicon grease applied.
I wiped the silicon spray off twice after hard rides and it has now stopped leaking out of the hub.
So moral of the story: use it sparingly !

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2014 XT660Z - Barrett pipe, DNA stage1.5, Barkbuster hand guards and handlebars, Pivot pegs, Teknik suspension, Guard-it engine protector combo, B&B rear rack, Trax topbox.