The bike is a Hero Honda Splendor Plus, and I've been seeing some fluid on the engine area for a month. Earlier I used to ignore it and wipe it off, but it returns. The bike's mileage has also reduced, which makes me concerned. I assume it would be some kind of oil leakage, because petrol would've evaporated immediately. Didn't see any obvious signs of tube cuts though. Pictures below.
I know I should show it to a mechanic, but before going there, I wanted to know what could be the probable causes and if it is something I could fix myself. Mechanics here have a habit of exaggerating the cause and overselling.