the oil gauge started going down last week and we did an oil change and filled it up but the oil gauge is now not working. Can someone help? Are there specific steps that I can take to check if its still working or if it is a glitch somewhere?

 

The sender is at the back of the engine, slightly towards the passenger side from the middle. Might check the connection. My gauge gets flaky every now and then, if I fiddle with the wire it will work again.

 

I put a tee on my sender and ran a mechanical gauge so now I have a direst read and the one in the dash

 

the oil pressure gauge in the dash is really nothing more than a glorified idiot light. it will read "pressure" if the oil pressure is over 7 or 8 psi. the sending unit is an on/off switch.
one of the first things i did with my trucks was to remove the oil pressure switch and install a mechanical gauge in them.