With engine idling, unplug one spark plug wire at a time, if you have a rod knock it will quiet down when that cylinder isn't firing.
That is what the "knock" is the rod slapping the crank journal when cylinder fires.
Running the 4 cylinder engine on 3 cylinders will allow you longer drive time, with less chance of rod breaking.
I drove 50 miles out of the desert with a bad rod, but that was a V8, so losing a cylinder was not great but could still make it up hills.
If knock stays no matter what cylinder is not firing then pull the valve cover, you have a rocker issue.
Once you hear a rod knock that's pretty much it, thicker oil will just thin out when rod heats up, the slapping also generates heat, next stage is the rod breaking, that can take out the block so fixing in now is actually a best case scenario since you don't have to buy a new block