I must admit one of the best valve oil's I've come accross recently is the 'Courtois' valve oil. It's very effective and very light, doesn't pong (like the Holton valve oil for example!) and works like a charm.
Soak the BOTTOM half of the valve in coke overnight (strips the mess off it - bit like the dentist and penny demo when your a kid - "this is what it does to your teeth you know"
Small amount of comfort (or other fabric softner) in water - (bout 1 part softner to 20 parts water) and mix... put it in a spray bottle (like trombone spray bottle or something) and spray on the rinsed valves. Softner stops the grease coming back and leads to fast valves - occasionally rinse and respray (like once a sheffield flood - or should that be a Tim Henman win)