I had a similar problem and just decided to to buy my test 400. I currently use test 400 and one of my vials broke. I initially asked people if i could just use the test-e and I got a few differenent repsonses. First off, it depends on what is in your sus. cyp, enan, prop? cyp enan decoanate? iso, phe, decoa? In the long run, with any of those, you will be "okay" but not optimal if you use the enan. what i wound up doing was buying a sus, an enan, and a cyp. It was a little pricey to do it this way, but it way i could make the concoction of test 400 i currently have. (cyp, iso, enan, prop, phe, dec). But like I said, knowing the ingridents of your Sustanon (sust) would help in answering the stablity question.