There not just for aluminum but Cadillac started using them in the 80's with the 4.5, 4.9 engines, aluminum blocks and cast iron heads. I wont plug up anything, I worked for Cadillac from 1998 till 2008 and it's in the owners manual and on a sticker under the hood on all Cadillac's even the Escalade.
If it was bad they wouldn't use it.
