Best silver shampoo?

Can any of you lovely ladies help me pick a good shampoo. My hair has a pure white streak (which appeared at age 40) at the front, mixed white and grey over the front sides but is still very dark at the back. It just looks dull. Would one of these shampoos work for me do you think? If so, which one.

I buy a 1.5litre bottle of LOreal Series Expert Silver for about £16-17 from Amazon. It lasts me just over a year using it twice a week. The bottle is huge! (And heavy) so I decant some into a smaller bottle to keep in the shower.

Why colour it Extrme Platinum? You are adding the blond/yellow tones that you say you want to get rid of.
Just stick with the Touch of Silver shampoo and conditioner and save some money!!

I use Aveda - Blue Malva - shampoo. It is actually a purple colour. I wash my hair with a made for grey shampoo first and then a second wash with the purple. I have tried cheaper purple shampoos but they made my head itch. The Aveda can only be bought in a litre size which is about £35 but I use one or two pumps each time and it lasts me for up to 18 months. If you decide to buy this shampoo ask for a pump as it makes the whole thing easier to use.