The greasy swing (not porn related)

[guids]

Ive read a bunch that you should have a real fluid, almost greasy swing. I dont have one, at least I dont think. when they say greasy/fluid, does that mean you just kind of throw teh club head up behind you, and let it rip? I find myself tense when I bring the club back, not jerky, but my muscles are flexed, and I conscientiously try to bring the club back real slow, so its not fluid (it may look fluid? I dunno). When I went to the driving range about a year ago, I just got in this groove with my driver where I actually felt fluid, I threw the club head back, and "picked" the ball off the tee, it felt good, but I havent been able to do that since. with my irons, I feel much more greasy for some reason, I think it maybe because its a steeper and more natural swing plan for me? thoughts, ideas etc.