John Freida colour inting shampoo and conditioner: Silly question?

[FleaDog]

I've not dyed my hair in years and ketting the grey cone through.

I'm having a wobble, and while I don't want to dye my hair again, I was looking at tje John Freia cool brunette shampoo.

My question is, does it completely wash out or does it leave any taint on the hair long yerm, in effect back to having some tidemark on my hair if i stopped using it?

I dont want to undo all my work spoiling the grey that's coming through!

Not sure about John Freida, but there's a thread here with some pictures of someone who uses Plantur 39

http://www.mumsnet.com/Talk/styleandd_beauty/4643812-dark-hair-going-grey

It completely washes out.

Thank you!