I use it in my freshly rebuilt h22, and haven't had a problem at all. I've run it in all my cars for quite a while now and have never had a problem. However, I didn't run it in all my cars for quite a while before that, and didn't have a problem either, so it's hard to say if it really makes a difference or not. I know people who swear by it, and people who swear against it. It is a fair bit of money though, but I do agree with the concept of it, and I sleep better knowing I added it, so I run it. In my h22 I run conventional oil (valvoline) and add the regular stabilizer, not the synthetic one.