1979 Subaru DL. EA71S swap (Factory racing engine from FJ1600). Unknown number of miles on engine prior to my ownership. Set up with single Holley 1904 carb on ported and modified single carb intake. GM HEI ignition module, Ford TFI coil, Denso distributor. EA62 oil pump with shimmed relief and Ford Racing 90 degree oil filter adapter. I put about 185,000 miles on it so far. Requires a valve adjustment every 10,000 miles because of the huge cam (305/305 advertised, I think, and unknown lift). Has titanium valve spring retainers. Power is 115 HP@6700 RPM, powerband starts at around 4000 RPM. 95% highway miles average cruising RPM 4,000. Oil temp runs around 100°C at that speed. Oil filters used are mostly Premium Guard PG4651EX, some Fram XG2/FE2/FS2, some old style Ford Racing FL820s, Sierra Marine 18-7758, and the occasional Fram Racing equivalent of the PH2. Oil used varies. Winter is usually Mobil 1 FS X2 5W-50, Mobil 1 Racing 0W-50, Mobil 1 Supercar 5W-50, Amsoil Signature 5W-50. Summer has been in the past, Mobil 1 15W50, Aeroshell W15W-50, Phillips 66 Victory 20W-50, Aeroshell 120, Mobil 1 V-Twin 20W-50, Total Quartz Racing 10W-60, Castrol TWS 10W-60, Total Quartz Ineo Racing 10W-60, Amsoil 10W-60, Amsoil Premium Protection 20W-50, Quicksilver 25W-50, among others.
Currently running Mobil 1 FS X2 5W-50, has about 3000 miles on the current oil change. I usually run to about 5000 miles. Any longer and the oil is "cooked". The hot idle oil pressure drops below 20 psi and I know it is time to change the oil. Attached is current oil pressure at hot idle.