Hey Ged
The Engine detail wasn't difficult to do, just time consuming, but well worth the effort. Hope the following helps (and makes sense).
Re : The paint work. I used the oil technique, let it set for 10mins and then wiped the excess off, once dried I then used extra fine steel wool to rub of the excess in the direction of where the desired effect would look natural. Painted the individual discoloured panels (red,greys and dark greys). Then using masking tape and Tamiya weathering kits some discolouration and the majority of the "oil" streaks, as a handy hint I used a Black china pencil that I got at Jacksons in Balcatta and a very good pencil sharpener to get extremely fine oil streaks. I did use my airbrush for the main engine streaks.
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Forgot to post the list of materials for the Engine Detail.
Evergreen White Styrene Strip 0.5mm x1.0mm (.02"x.04") 10pcs Length: 35cm (14") = Grill
Evergreen White Styrene Strip 0.5mm x 2.5mm (.02"x.10") 10pcs Length: 35cm (14") = Grill, End capping for Large Baffles (blue)
Plus Model #073 Styrene Sheet - Thickness 1.0mm (2 Sheets) = Large Baffles (blue)
Evergreen White Styrene Strip 3.2mmx4.0mm (.125"x.156") 6pcs Length: 35cm (14") = Small Baffles (red), Curved Middle Support (green)