Hi Bkutsi!
I assume you are using standard Glycol/Alcohol Antifreeze. And no, I am not aware of any formula changes. As to your leaks, I would suspect your fixture. If it isn't that, then it's bad antifreeze. Standard Glycol/Alcohol is good down to -50F. Whatever the reason, you won't be able to find the cause until you hit warm weather. Wish I could tell you more.