bought my daughter a 94 Mustang with a V6,cheap because the used car lot was sure the engine was about dead. It would run about 10 mins then the oil pressure would drop and valves started clattering.
I changed the oil and filter,cheapest stuff on the shelf,then started home,about a 30 mile drive. The oil pressure would drop after about 3-5 miles I shut it off and restarted and had pressure,drive repeat.....
Stopped at the local parts house,picked up 3qts of motor flush and 8qts of the cheapest oil they had and 3 filters,again cheap ones.
Got home drained the oil it looked like tar after only 30 miles,changed filter added 3qts oil and 2 motore flush. Fired it up and walked away,not far away,lol. When the lifters rattled I shut it off and waited about 10mins then started it again. I did this for about 3 hours,the last 45mins it held pressure.Drained the chunks out,changed filter,1qts flush 4 qts oil and went for a drive and gas. In the next 2 hours it never lost pressure.Drained it again and put new filter and 5qts of Mobil 1 car never had another problem for 25,000 miles then we sold it.
Do you know the history on the car? If not it could have been owned by the same person who had this Mustang,added oil but never drained it.The synthetic oil may have desolved some crud and let it float around to the oil pick up but wasn't the cause.
THe instructions on the motor flust say don't drive with it in so be ready to stop for a couple oil changes on the way home,I might even add a qt of motor flush and carry on.