Your source needs better info and advice.
Winstrol is winstrol. The half life is the same no matter what it is suspended in.
I mean really, if these guys don't understand how to use what they are making, they shouldn't be carrying it.
The ONLY advantage that oil base winstrol has over water based is that #1 it is less painful (no sting if made right) and #2 you can make it at a higher concentration in oil than water.
That is all. Otherwise is still winstrol.