cleaning my motorhome

hi there,

can anyone advice of the best thing to use to clean the sealent around the locker boxes wheel arches joints etc, my van washes up really nice but the sealent is always a bit black and grubby looking

secondly, i have seen a product (cant remember its name) which you spray onto the bodywork leave to dry and wipe off no water needed does anyone no what it called and had any experience of it,

thanks