If the owners manual says 5 quarts, put 5 quarts in it. Run it for 30 seconds or so and let it sit for 10 minutes, and then check the level. If it doesn't read full or safe(depending on year), the stick is wrong. In the late 80's and early 90's we had a ton of oil consumption complaints, especially with 302/351 F trucks under warranty. An oil consumption test is required before a repair attempt so we'd change the oil and filter, run the engine, and check the stick. Many. many times the stick read low so we'd cut the appropriate length off the dipstick tube to correct the reading. Then the customer would drive the truck and monitor the oil level, if it was low he'd come in so we could check it and document the mileage. If less than 1500 miles/qt, we'd tear it down. We found one 89 F150 with no oil rings at all on some cylinders but almost all complaints were solved by correcting the dipstick.
The town of Canaan had a Crown Vic cruiser that was using oil so we did a consumption test. After 2000 miles with Motorcraft oil it was still full so we gave it back and the chief sputtered. It came back with another complaint so we repeated the test with the same results. It burned the Amalie oil they used but didn't burn any Motorcraft. I finally got it through his head that the only difference was the oil.