I have a 1990 b250 ram van and the oil gauge reads low or not at all? Change the sending unit out, was working good untill now. If I drive it for a little bit it started to read normal? I cant figure it out ant help with this would be great.Thanks

 

The gauge itself could be bad. The only way to know for sure is to remove the sender and screw a gauge into it's hole to see what the real pressure is.