Go to wherever they sell body shop supplies and right beside the Metalprep you will see Alumiprep. That's the stuff you want.

Another good product is Steamiron cleaner that you will probably find in a hardware store but its probably the same chemical as Alumiprep but in a smaller bottle and more money.

You say you want to do the inside but that is going to be fuel and exhaust residue and the acid cleaners won't touch that. For that you'll need something like carb cleaner.

But when have you listened to me ?!?!