Unfortunately getting the red flashing oil pressure light is pretty serious. It means the engine is not getting sufficient oil pressure to keep all the engine internals sufficiently lubricated, resulting in extreme engine wear, which is why it's so important to get this fixed sooner rather than later.
Low oil pressure can be as a result of different things, I've sorted them by how easy it is to check them:
-Oil level being too low/too high.
-Incorrect oil grade (correct oil for this engine is 5W30 or 5W40, depending on mileage and tuning).
-PCV valve failure.
-Oil pump pick up pipe clogged.
-Oil pressure sensor failure.
-Oil pump balance shaft/shaft sprocket bolt failure.
-Worn piston rings, connecting rod bearings or main bearings (unlikely unless it's a really high mileage engine).
-Oil squirter failure (also very unlikey).
Hopefully you can figure out what's wrong before it's too late. These aren't cheap engines to replace and they are notorious for low oil pressure. Also it's important to note that oil pressure is only is not measured at idle; the sensor only checks the oil pressure above ~1200rpm.
I would always recommend buying an oil pressure gauge but it's a massive hassle getting the oil pressure sensor out on these engines so up to you on that one. If you do decide to get one here are the specifications your engine should be meeting when fully warmed up:
Also, were there any suspicious rattling sounds or a burning smell when you had low oil pressure?
