Not pointing fingers, but who services this car? It takes many months for them to get that low unchecked. The wheel sensor warning comes on about 25 psi(not the safest and not good for the tires, but ok at city speed), that's 10 psi below the required for a 245x45x20 tire. It only takes 5 seconds to check on the dash display. Now the oil light. As said prior, 0w40 synthetic every 3,000 miles. It's good for 5,000, but the "Dealers Service Required" message will display for 10 seconds at every start-up after the 3,000 mile computer reset. Unless there is a computer or sensor glitch, I would say wrong oil or lack of timely service or both. Unknown driving habits and engine mileage might also play into this. How much oil did you add? The 6.1 holds 8 quarts. I don't know for sure, but I don't think the light would come on if less than 1 quart low.