I had been running Mobil 1 5W-20 Extended Performance and occasionally getting an oil analysis over a period of 10 years. Copper wear had been running higher, 8/10/10 ppm for 4100/4300/3750 mile oil change intervals. Universal average is 3ppm for 4400 mile interval.
The last test in ‘22 I ran 5 qts. 5w-20 EP and 1 qt. 0W-40. Copper wear dropped to 6 ppm on a 4600 mile change interval. But we had been taking it out more often too so it was sitting for shorter periods of time so perhaps less top-end start-up wear.
cST viscosity has increased too from 8.0 to 9.92 just out of the top end of the 5W-20 range of 6.0 - 9.7.
So I’m now running what ‘appeared’ to help, 5 qts. 5w-20 EP and 1 Qt. 0W-40 with a Napa Platinum filter. The platinum filter has full synthetic media.
One car works well with 0W-40 instead of 5w-30 (0W-40 is thinner now, Cst dropped from old oil 12.7 to 11.3) so I have plenty of that and use it for top up here and a 0W-20 car.
Could try 5W-30 synthetic but would have 4 quarts sitting around for up to 18 months. Easier to use 5W-20 5 Qt. jug and add a qt. of 0W-40.
