I have used this in IHC engines, which are well known for blowby, works good.
I use it in my 305 gmc v6 for the same purpose, works even better for blowby in that engine. Watch how much you use, it thickens up the oil quite a bit, I have talked to a couple of guys who used it in from day one in 250k mile 454 engines. I use Rotella T 10w40 in the GMC. It makes the oil sticky and the websites say it is "old technology", but I like it. I put 1qut in with 5 of oil for a six quart fill up. I use in on NOISY transmissions. I know a guy who puts it in big truck transmissions, I have seen for my own eyes that it brings down trans temps 20 degrees. Might be something better, but I bet its not cheaper.