I used a dual approach, firstly I sprayed carb cleaner on to get it moving (not cheap but did the trick) then using a stiff brush, like a garden brush, I worked in loads of Swarfega oil and grease remover (from T**lstati*n just under £9 for 5 litres) and then used the power washer on it. After a cou...

We use the collodial black from St**ax, maybe twice a year. It really does come up like new! I cant remember the price but it didnt break the bank. It goes on a treat too.