low oil pressure gauge

[lg95ranger]

I have a 1995 Ranger 4.0 4x4 5 speed..the oil gauge fluctuates between low and mid range. This is a scary feeling when I look down at the gauge and see no oil pressure. Is it a sending unit,or do you think maybe the pump is going bad. I use 15w40 oil in this baby..she has 170k on her..Please help!

 

[Explorin94]

Why are you running such thick oil? I know you said it has 170K on it but 15w40 is a bit much. The clearances of that engine so close and that 15w40 has a problem getting where it needs to be. First thing I would do is take the 15w40 out and put a 5w30 or 10w30 in it to see if the pressure will come up. If that doesn't work put you a mechanical opil pressure guage in place of the stock oil sending unit. That will give you a good idea where you need to go next.