Carb and brake cleaners do very little and expensive conidering the amount needed.
We used parafin applied with a brush to clean off decades of grimed on grinding dust to congealed hardened oils.
The oly other thing found is the cheap £1 spray on Elbow Grease found in pound shops and the like, works superb on alloy wheels.
Discolouring of aluminums is oxide and will need stripping to some extent