My Ford Explorer with V8 5.0L engine, had an issue with oil pressure since I have bought it (used, 83k miles). Those engines where designed in 60's, with 20W40 in mind, sold in Explorers with 5W30 and, in the last two years of fabrication (2000 and 2001) where sold as taking 5W20. Mine is a 2001 and it had a horrible tick, sounding as a diesel. With engine warm, at idle, or even at 1200 rpm (with 5W20), pressure would drop to the point of pressure needle bouncing violently (it's a dummy switch for 5psi). I have used a real gauge to measure the pressure, and the issue is real - once warmed up, idle pressure is almost non-existent. I even tried a lower temperature T-Stat - helped just a smidge (took longer to do the jumping dance). Tried 5W30 - no change. Tried Rotella T6 - almost good, but still needed some Lucas or Motor honey to be completely quiet. But those will wear out eventually and start doing it again before the 5000 miles mark. Tried Mobil1 5W50. It was good from the start, but eventually still starting to be 'jumping'. Longer lasting of all. Tried Liquid Moly at the end of the oil change interval, and that made quiet back until I was ready to change oil. Well, since it was spring, summer coming, I decided to try Valvoline Synpower 20W50 - hoping that base oil starting at 20W will have less additives (to wear out), lower volatility. I am at 3000 miles now, time when it was starting already to sound like a diesel. Wow, still quiet as was in the first day. Almost unbelievable after all those years of lifter noises and needle pulsating at idle. The gas mileage didn't increase, but that truck is now driven more around town, so idling at lights and constant acceleration/breaking is what mainly affects the mpg. Vis @ 100°C (cSt) = 19.0 Vis @ 40°C (cSt) = 139.0 NOACK, wt. % loss = 8.2 Sulfated Ash = 0.78 Zinc/Phosphorus, wt.% = 0.084/0.077 Calcium = 0.193 So.. I found my magic oil.