Yellow oil light in speedo cluster

[JDM VANMAN]

The oil light in the speedo cluster comes in when I first start up the van but after driving it for bout 15 minutes a goes away. I just had a full tuneup done so I know there's oil in there. When the idle is low the light comes on and the oil pressure needle is pointing towards low, once I start going the needle moves up to normal and the light goes away. I know my Celica would do the same thing but it was burning and leaking oil every 2000 miles so I would just add oil and keep rolling. With that said I've only drove the van 50 miles since it came back from being rehabilitated.