[Craig]

Ricardo,
The oil change procedure is pretty straightforward. But, when you drain the oil be sure to drain the engine AND the oil tank, not just the engine. The oil tank is on the right side of the car behind the right rear wheel. Have a big pan ready with a big opening to catch the oil, becasue the oil drains FAST. Replace the oil filter, and then fill with oil. I usually put in 10 quarts, and then start the engine and check for leaks. If no leaks, take it for a short drive, enough to warm the car to operating temp, then check the oil level - car running, level ground. Add more oil as needed, most like to keep it halfway between the marks on the dipstick.

My 77 has the 140 psi gauge also, never thought about why. But on cold, Colorado winter morning, my pressure has been at 95-100 until the oil warms up a little. I don't push the car at all until the temp gauge gets to around 100 degrees or so, and the pressure drops into the normal range. Takes about 5 minutes.