To Dye or Not To Dye

I'm been growing the dye out of my hair since spring, and letting it go fully grey. We're heading off on a big trip for three months soon and I didn't want to be fussing with hair dye.
I thought this stuff would shift a bit more of the colour and make me look a bit less badger like, but it had very little impact on my hair. Oh well, just have to do it the slow way.