I had forgotten how good white spirit was at getting years of grim off. Decided late this afternoon to have a go at removing more of the years of grim from the underside of Z's bonnet. When I bought the car in December the underside of the bonnet looked like it had never been clean since the day it was delivered in 1998. When I bought the car I attacked it with nearly every cleaning agent I had in the garage, yes it removed a bit but the bonnet was no where near how I wanted it (it still looked ). So this afternoon I attacked with white spirit and 2 cloths, after 2 hours and a few numb fingers it looks loads better and nearly all of the grim is gone. Will attack again next week. You may ask why I didn't power wash it off, mainly due to the fact that I didn't want to have water and spray everywhere. So forget all your expensive cleaners and break out the WHITE SPIRIT.