Did some searching on here but didn't see this one. I have an 85 Chev, 305. The oil pressure, after the truck warms up, fluctuates at low speeds. Could this be an oil switch or sending unit or am I getting ready to grenade? If it is a switch or unit, where are they? I can't find a pic anywhere or a description. From what I've gathered here, there is a switch that has to do with fuel pressure and then a sending unit by the starter. Correct?