Perhaps a bug on windshield.
if it was like my 99, then a belt was worn out, and will cause a chirping noise, if it is in the engine compartment, it is very likely to be a belt
Many things, but a clutch bearing seems likely.
Most likely cause-valvetrain noise, check oil level, pressure, also possible engine knock. If you have a knock sensor, mil should be illuminated
Not likely. A bad O2 sensor would illuminate the check engine light and the engine performance would suffer.
Depending on the vehicle, it most likely needs adjustment.
Most likely is knocking. Try next higher octane grade of gasoline.
Engine running hotter then 220 degrees can cause valvetrain noise. Bad fuel can also cause valve noise / PINGING sound. Ignition timing to high / Advanced to far, can also cause engine noise.
A bad harmonic balancer can cause a knocking noise. The harmonic balancer doesn't actually produce the noise, but it can cause the noise in the engine.
The A/C system compressor operates when in the defrost mode. If the noise is also heard when running the A?C it is more than likely a problem with the compressor/pulley.
You more than likely will not hear any unusual noise. However, if you overfill the crankcase this can cause engine damage. The crankshaft will make contact with the oil and create a froth. This froth will contain air mixed with oil which makes a poor lubricant. This will cause engine wear. If you suspect the engine oil is overfull simply park the vehicle on a level surface, wait at least 15 minutes after the engine has been shut down, and check the oil level. If it is overfull, drain out enough to get it down to the full mark.
cold engine
No