Any detergent or solvent that is caustic in nature (opposite of Acid) will discolor aluminum. Most cleaners like oven cleaners, automatic dishwasher soaps, and even Tide laundry detergent are caustic. Dawn Power Dissolver is also slightly caustic.

Some of these like the Dawn Power Dissolver are OK as long as you do not let is stay on the engine for extended periods or boil the part in the power dissolver.

There are paint strippers that are supposed to be aluminum safe.