Back when I ran AC's, they always had black ADBV's. Silicon is usually orange. Having once had sludge problems, I am running short OCI's and never had trouble with a black ADBV. If you are running longer OCI's, and have had trouble in the past, you may want to check further.
Silicon ADBV's may be one more thing some overly obsess over. For me it is short OCI's and sticking to Pennzoil.