Ironically the suspension is more apt to hurt, but depends on the pulverization process or how finely micronized the powder is. I always consider how different stanzolol/winny can feel. If it clogs the pin damn sure it will hurt like hell. Some labs would emphasize the word micronized as no clogging and minimal pain.
Winny in oil was rare long time but the same high dose in oils was painless compared to same in aqueous suspension. Again can depend on compound . I went to pharmaceutical conference for some injectable psychotropics for job and the speaker tried to say that the new shot would hurt less cuz being in water, however I had 8 clients with me who actually get the shot saying the oil was painless and the new water suspension was excruciating . I believe they micronized more in oil plus I'm wondering if the oil also serves as lubricant