It is not always a matter of volume of oil.
People have all different combinations of rev rate and ball speed. The ratio of speed to revs is an important criteria for the strength of ball needed on various oil amounts.
When you're speed dominant (ball speed is high in relation to your rev rate), you can, in fact, need to use much stronger balls than if you're matched or rev dominant.
I have a friend who is speed dominant, even though I'd estimate his rev rate to be around 175. On the same amount of oil on which he uses a Sinister or a Lucid to play 8/9 at the arrows out to 5 at the breakpoint, I, who am rev dominant, am playing 17/18 at the arrows, getting it out to 7/8 at the breakpoint with a Tropical Breeze. Needless to say, between the very strong balls he is using and his far outside angle, his carry percentage is much higher than mine.
Such is life.