I have two garden benches, which I bought a couple of years ago. They have now turned a horrible, dull grey colour. Is there an easy way of restoring their colour, without too much messing about?
Unfortunately no......I had a bench do the same thing once.....to get any nice colour back your going to have to get handy with the sandpaper and then a good outdoor varnish....either that or just paint the thing but you will probably need to sand it first for a half decent finish anyway.
If you don't want to mess about then you could try teak oil if they are hardwood...you may not want to though in case it comes off on your clothes. Personally I like the silvery grey colour
We used a very good wood varnish to paint our last years bench which looked brilliant - until the sun turned the varnish into tiny balls of sticky resin.
Woofgang's suggestion is exactly the same as the furniture supplier - teak oil.