dodge d 150

Just bought a 1988 dodge d150 the first time i start it during the day my oil light is on for about 10 min w no oil pressure registering, Then after it warms up the oil light goes off and the pressure increases to a little more than low ( about 2 ticks above low). I only paid 1000$ for it and dont want to invest alot of money in the truck. Any idea what the problem is and or a cheap fix.
thanks
hoptoad

Is there oil in the motor?

yea it was low but i added oil yesterday and it had the same problem this morning

yea it was low but i added oil yesterday and it had the same problem this morning