Proline winny is oil based and has gotten great reviews from users. Oil based suspensions such as winstrol are good because they are less painful, and bacteria is less of a problem. There is no evidence that oil delays the release of the drug or prolongs its half life through another mechanism. For that you would need to attach an ester and winstrol already has a double carbon bond in the 17th position. So in summary, oil based winstrol:
1. Is less painful
2. More sterile
3. Un-altered frequency of injections