@RMT, dude I strongly recommend you clean that rad -
- Remove the fan, surround, guard & side guards - be careful undoing the 3x 10mm screw nuts, if them wont budge either gently hold the rad spigots with pair molegrips or worst case cut the bolts off with a dremel.
- Then give the bare rad a soak it in the bath with a small amount of washing powder to loose and remove all that crud.
- Then get it "very gently" soda blasted (its soft enough not to cause damage).
- Then if the rad still looks sound, go buy a can of grey etch primer and black gloss (3-4 thin coats of primer and then 3-4 of black leaving enough time between coats.)
- You could either get the fan surround and front guard powder coated ot just get them soda blasted and paint them as well.