Just done parts of my black engine gen1 with RS paint, not cheap but almost impossible to tell the difference between old & new. If your scratches are large enough & in a position that you can use an aerosol rather than touch up brush it will blend in better. Don't forget your etch primer, you can use Halfords grey etch primer rather than buy RS as Halfords is compatible with the black RS gen 1 engine paint. If you want a pic of my engine let me know & i'll bung one up for you.