Hey! I am asking the questions here!
If your oil pressure gauge is high you have to much oil in your engine. Overfilling your engine can result in you blowing out your gaskets.
Faulty PCV system or engine blow-by.
I'm not a mechanic / technician but I believe that a plugged PCV valve or hose will cause oil to blow through the engine oil dipstick
Blowing black smoke is indicative of an oil leak in the engine.
You have overfilled the engine. Drain the oil to the appropriated level.
Yes, you can mix them.
I have Toyota 2l-T engine the problem is the oil blowing on the exhaust is this the turbo charger problem?
It's for blowing your top.
Yes. The oil will expand as the temperature of the engine increases leading to numerous problems from blowing gaskets to aerating the oil which leads to poor lubrication of the main components. In a nutshell it's can be as bad as underfilling.
Engine oil could be running too rich or rings!
possibly however if you use a heavier oil you run the risk of your engine not being able to pump the oil required to the parts inside and blowing your engine
One reason could be an extremely worn engine, another possibility is way too much engine oil has been put into the crankcase.