Blender has a built in fluid simulation engine. Conveniently there are options to simulate oil and honey as well as water; alternatively you can change the properties of the fluid directly, change the way that it sticks to or flows along obstacles, or cheat by accelerating or decelerating the sim. Whichever way there's a lot of trial and error involved in setting up a scene and even at a low resolution, "baking" the fluid can take a while. Oh - and you'll need some serious hard drive space to try this.
Here I'm trying to add a fluid simulation into some mini-DV footage, tracked painlessly in Voodoo and then mapped in Blender with some (non-simulated) elbow grease.
The Blender interface reminds me of the flight deck of a 747 - too many buttons. Trying to get a particular effect to work as expected often descends into a hunt for the one tiny, unlabelled button that I've forgotten I pressed earlier - for me the worst culprits are the row of portraits on the far right that exclude objects from the final render.