About to continue doing this myself, except my cause has been slightly complicated by a previous owner (or more likely somebody on behalf of the PO) has applied either black Waxoyl or black Dinitrol to the inner arches and behind the front pu....I'm debating whether to clean and keep it, or continue to try and remove it (a bugger of a job on the original anti-stonechip surface)...anyway, not wanting to hijack, but in researching again last night, I found
this guys writeup on Detailing World....very nice job he's done too.
He hasn't done an engine/box removal but did go to a lot of effort into other greasy and grimy areas, using a product called Tardis. A nice quick thread to read....quite inspiring too. (Think he's also quite local to me in the UK)