Mine are badly contaminated with fluid from a previous set of brakes and I need to clean them up before fitting my new brakes.
Oven - ours needs a clean itself, so may leave greasy deposits on the discs
Petrol and match - could do, but won't that leave a tarnish?
Dishwasher - anyone tried this?
Finish Line disc brake cleaner - got some so will try this but worry it won't be man enough.
Any other ideas that have worked well?