Leak in engine

[foggpogg]

Hello
I have a leak of some sort and cant work out what it is. Back left side of engine whatever is leaking is solidifying and becoming crystallised / crusty.
Any help appreciated
Cheers
Foggpogg

 

[Crasher]

That is an Add Blue leak, it is synthetic sheep's urine which is why it crystallises.

 

[foggpogg]

Cheers