Oil pressure fluctuating and then shows zero no pressure

This is one of a couple things. First and foremost, this is an issue with the type of oil you are using. If the oil is too thin then you can get crazy operation.

Next the most likely thing is a failing oil pump that is not keeping constant pressure.

https://www.2carpros.com/articles/high-or-low-engine-oil-pressure

However, the thing I suspect this is and the most likely cause is you have metal floating through the system and it is contaminating your variable timing valve system.

Basically there is an oil control valve that is in the exhaust cam shaft and this will alter the timing of the engine to optimize the performance.

Here is a guide that talks more about this:

https://www.2carpros.com/articles/how-camshaft-variable-valve-timing-works

Below you will find the detail on how to replace this. Please run through this info and let us know what you find. Thanks

Thanks all guys. I fixed the problem which is oil sender unit. Now my car engine sound is back to normal.
Thanks again.

That is great info. Thanks for the update. However, that is the oil control valve/actuator that I was talking about.

Thanks again for coming back and updating us. I am sure that info will help others in the future. Thanks for using 2CarPros.