I am completing a Leopard 1A4 of italeri as a tank of the West Germany Bundeswehr in the '80s, with a gelboliv uniform finish.
I have seen lots of photos of such tanks with temporary camouflages made with brown or white spots on the dark olive base.
Now I ask: the white paint is certainly distemper or something similar, but the brown blotches are made with some standardized distemper or with mud? If it is a standardized paint, is the exact shade known?

Mud camo was often seen on 1A3 and 1A4. Mud up your model to your heart's content:-)

Definitly the Bundeswehr used mud for temporary camoflage. an old Tamiya Photo Album shows a Leopard 1 A4 with mud camo. I think that a mixture of Tamiya XF-60 and XF-52 would do. It looks a little like a darker hue of Dunkelgelb.
This is what I mean.
https://www.google.de/search?q=Leopard+1+Schlamm+Tarnung&sa=X&tbm=isch&tbo=u&source=univ&ved=0ahUKEwj_rbWDz-PTAhUJfiwKHe8zAYwQsAQIIQ&biw=1440&bih=761#tbm=isch&q=Leopard+1+Schlammtarnung

Thank you, I'll do so.