MD6 & SUSTANON 250

I just bought MD6 and have been taking it for a week, I love it. I am afraid of losing muscle while I diet down, I am thinking about taking 1 redi-ject of sustanon 250 a week for 3 weeks in hopes that this will allow me to retain my muscle while losing fat, Bill, I was hoping you give me your opinion on this. Please keep in mind that I do not expect to gain any size, I just don’t want to lose any. Thanks-

I was alos wondering if injectables go bad, especially larger bottles w/ the seal broken?