2007 Ford F-150 Dry engine crank and run

My son was changing oil on his 2007 Lariat 5.4 flex. Its been solid, no engine problems (other than usual tuneup plugs issues), and only has 75k miles on it. Fluids have been switched to Amsoil synth. Well.
After draining oilpan, he realized he needs filter wrench to take off oil filter, so he simply pours ONE quart 5-20 in, and hops in for the mile long ride over to shop. Said halfway through he felt motor grinding almost to a stop but made it to the shop, where he filled remaining oil before coming home. Well, since then its been driven about 30 miles or so with no nocking or grinding of any kind. Ive also scanned it with SCT tuner and no codes have been thrown. No overheating or any temp or level problems so far either. But when I drive it it feels to me as if I'm needing to push it a lil harder on the gas for it to get it going. Also feels rougher and shakier at higher speeds.
So my question is what would be the best way for me to check weather anything in the motor really sustained any kinda damage adn what kind really. Hopefully other than running some expensive diagnostics. Also, regarding what could be issue, is running the 5-20 synthetic optimal, or should something heavier be used? Ive heard pushing it at 3500 rpm for 10-20 min continuously would rattle out any issues. I dont mind exacerbating any problems, my main concern is identifying them. Thanks and any advice appreciated. Oh yeah, and would matter that its a 5.4 flex mean anything? Trucks been run on plain unleaded since new, I dont even know what the flexfuel stuff is/means. Thanks