randomly my oil light will start flickering. sometimes it stays off for days but other every now and again it will start flickering. wth?

 

Sounds to me like a short in a wire, check at the oil sensor and at the back of the light bulb first. those will be easiest. Is the oil level sufficent?

 

Before you assume anything you should verify that you have sufficient oil pressure, the light is supposed to come on when the pressure is too low. Until you know that your pressure is good you could be doing serious damage to the engine.

 

Yep. Gaie is right.
If it were me..
I would put thick 15w/50 oil into it and a good Wix filter. Not a junk Fram filter.
Weather is too hot to be running thin synthetic Mobil 0-40w voodoo oil.

 

Go to harbour freight get a cheap oil pressure guage and verify your pressure before your buying a new engine which is a bit more then a $20 gauge.

 

First, heavier oil in not a fix for a possible low oil pressure issue.
You need to have the pressures tested at a cold start, at idle and 2000 RPM's and agin when warm at idle and 2000 RPM's. Do not waste your time and engine messing around with any other test.
Also, quit driving it cause if it is the oil pump, every time that light comes on you ar causing damage to the engine.

 

We need to know what year your truck is and how many miles are on it.
Also where do you get your oil changed and what oil are they using?
5w-30 is to thin when it gets hot and can cause the oil light to flicker at a hot idle.
I have no idea where you live, but if its been well into the 90's and above, my money is on the motor oil being to thin when hot.