Question

why water droplets slide faster than oil and sugar syrup on the a tilted box

Answer 1

The answer is “viscosity”. This word was mafe famous (in my mind) with a series of car engine oil commercials that warned of the dreaded event of “viscosity breakdown,” and through that, the elimination of helpful properties of the oil.

If you heat up the oil, then you can get it to slide just as fast as water. It all has to do with intermolecular forces like van der waals, and other small but additive forces.

The “water slides faster than oil” is just a fact that references our usual atmospheric conditions, and how oil and water behave under those parameters. I'm sure you can find an oil that still flows at 20 degrees farenheit - and at that temperature the water is unlikely to move, as it's now a solid (ice).