Marvel Mystery oil, or a similar "top end" lubricant, after an oil/filter change.
Depends on the age and valve system on you car.
They could just need adjustment.
Modern engines use hydraulic valve lifters. If these persist in rattling after warm up, you could have a worn camshaft and/or vlave lifters.
check the spit valves
Take it to a mechanic.
Is your oil level?
replace the exhaust.gmjim
Replace the valves guide seals.
Your furnace may be rattling due to loose components or a buildup of debris. To fix it, you can try tightening any loose screws or bolts, cleaning out any debris, or contacting a professional HVAC technician for further inspection and repair.
Rattling under the hood can be something easy to fix to something bad. It could be loose bolts, bearings, pulleys, or it could be interior in the motor.
Your bike chain may be rattling due to it being loose or worn out. To fix it, you can try tightening the chain or replacing it if it is too worn. Make sure to also check the chain tension and lubricate it regularly to prevent future issues.
Bash it with a rubber mallet while it is rattling. Seriously. Mine stopped.
sounds like your valves are rattling check your oil
Need more info. It can be $5 for a Tire valves to $2000 from bent valves/damaged pistons.
You probably have a loose blower wheel. Call an AC tech to fix it.