There is a gurgling/splashing sound in my 2002 impreza wrx, the loudness is proportional to the engine RPM and happens in gear and in neutral. It seems to come from under the car between the driver and passenger seat. There is no warning lights and nothing is leaking underneath.
I changed oil a few weeks ago, so my first thought was maybe I didn't tighten the oil filter or the drain plug.
This morning I checked oil and it seem low, so I added another quart. But the gurgling sound is still there when I drove it. I waited a few hours and checked oil again and now the level seems too high by about 10%.
Could improper oil level create this sound? I cannot think of other parts that contains enough liquid to generate a gurgling sound. The car is stick shift.