How do I get my whites whiter?

[lizwizz]

Despite using well known brands of washing powder I've noticed my whites are looking distinctly grey. Is there anything I can do, short of buying new clothes? It especially applies to shirt collars, but mud doesn't seem to completly come out of T-shirts either.

[little coojy]

BIO TEX it gets the mud out of my 11yr old football mad sons, just soak it in a bowl then wash as normal.

[Postdog]

Yeah, every now and then I give all my whites a good boild wash with added whitener. Works a treat.

[curiosity]

I only wash whites with whites and use Glo White sachets or Vanish powder on the intensive cycle.(usually near the detergents in the supermarket)