Engine knock/rattle only on warm start and occasionally stalls on warm start
 

2012 Santa Fe with 80k kil.

On warm start, and it gets worse the warmer the car is, the engine knocks or rattles. It only lasts a second, maybe 2. It is something internal so no heat shields or starters. It almost sounds like a diesel.

Once it is very hot, if I turn it off and wait a min or two, it will make an even louder noise and stall. Once I try to crank it again it will start. Rpms go up and the right back down.

It always starts cold and almost all the time warm, just with a horrible noise

I tested and tried all ignition components. None of them seem to be the cause. I even replaced the temp sensor.

Mechanic thinks it could be bearing, oil pump, lifters, caked pistons. I live in a third world country, they don't diagnose, they fix. So, I was told to wait till it fails completely and then they'll fix it.

Only thing I can think to do now is to try and find a STP additive and try a thicker oil. Any suggestions or help would he greatly appreciated.

The engine doesn't care where you live.

It is trying to tell you something and the longer you ignore it the more expensive it will be to repair.
Anything that causes an engine to knock should be investigated and repaired before it leads to more extensive damage and increased costs to repair.

Engine knocks DO NOT repair themselves and the longer they are allowed to continue , the more it costs to repair.

There are no "band aid " fixes for this. Wish we could be more helpful, but that is just the way it is. Good Luck.