I have searched through some threads on this product, but couldn't find consistent answers to a couple specific questions I have.... 1. The bottle I have was given to me over a year ago... it still has most of the product but it has been unsealed the whole time. still okay to use? 2. Some of the posts I read alluded to the fact that it was meant to be run by itself w/ distilled water and no antifreeze?? Is there any harm if I add it to my cooling system as it is right now? I was just going to take off the rad cap and pour it directly in. By the way this is for my 96 SSEi, which has a 50/50 mix of tap water and Autozone brand long-life antifreeze. The antifreeze is about 9 months old, give or take. I guess I basically want to know the most effective/ safe way to use the product. It's just been sitting on my shelf so I thought I may as well use it in the car that gets beat on most.