when vehicle is started it may register the oil pressure or not. It stay off or come on for a while then go off. There is no rise of temperature of the engine.
Oil gage fluctuates from registering pressure to off. It does this intermittenly. on 2005 GMC Savana 3500
i would have the oil pressure verified with a manual gauge first. it may be a bad sending unit but you need to be sure. try our directory tab at the top of the page for a shop near you.