Don’t put five bottles of STP in your engine! It’s not oil!
I questioned the 5/20 because it is not what your engine requires 10/30, 30W 10//40 or 40W, the 5/20 is for late models and there engine design.
The late model engine is designed for absolute efficiency trying to get the last half mile per gallon out the gasoline possible and the thin oil does that so bearing clearance are built with that in mind. There also built to run with fuel injection so fuel wash in the oil isn’t the problem it was with carbureted engines. So use the correct oil not 5/20.
Part of your massive oil leak might be using the thin as piss oil you have.