Oven cleaners are typically sodium hydroxide based, with various stuff added to mask the noxious odor. This is lye, caustic soda, powerful alkali (opposite of acid). It turn grease into soap, this is why it works on gummed up ovens. Very reactive with aluminum, the can should have a warning not to use it on aluminum.
I would look for something else. It will etch the metal. May leach AL out of the alloy as well.
If you do try it, keep an eye on it and be ready to rinse it off fully after a few minutes as grcamna2 says. Not sure how great it is if you have to go at the metal with steel wool afterwards.
Soda or CO2 blasting is the best engine case cleaning process I've found.