Fully synthetic
Not likely. If you have a noisy lifter then its oil port is probably plugged because you didn't change the oil and it's too late for synthetic oil to help you. Try it, though, because the alternative is a lot more costly.
Why yes. Loss of compression in that cylinder that has noisy lifter.
Sometimes depending on why lifters are noisy. If there is a piece of dirt stuck in one or it's damaged it needs replacing
For noisy hydrolic lifters (eg Mitsubishi etc) Get some : PRO-MA MBL8 OIL ADDITIVEThis stuff works great and keeps them quiet for about 5000km in my turbo lancer
A tapping noise in a 2002 Camaro could indicated noisy lifters. Make sure that the oil level is full, and the oil is clean and recently changed. Lifter quieting additives can help reduce the noise some.
When you say "clatter" do you mean lifter/valve noise in the top end under the valve covers? Dirty oil will make the top end noisy because it is not lubricating enough to protect the components. Or the oil pickup is clogged. Best to change the oil if you know it is dirty and see how it sounds after that.
First check oil level. "Loud clattering" can be lifter noise you are hearing. This can indicate oil is not reaching the top of the engine or worn valve train parts. Another reason for noisy lifters could be the oil pickup is not picking up, could be clogged.
pump it full of motor oil with an old squirt oil can
a clicking sound usually indicates a small exahust manifold leak or a noisy hydraulic lifter in engine if no exhaust leak, check to see you are using correct viscosity oil and a good brand, not a cheap recycled brand such as you get at walmart
worn out lifters or rockers maybe then oil
Lack of oil changes.
Sounds like a dirty valve lifter or maybe the lifter lost prime. I suggest changing the oil using something lite like 5w30 . Also ass a can of CD2 or vave medic. They are both made for quieting noisy lifters Also chech the oil level weekly to make sure you do not run low again.