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All of the Subaru 2.4Ts have oil coolers, so copper in these is generally NOT from bearings. At less than 20k miles, this is likely still normalizing even though it went up some here.Silicon from an air filtration issue seems a little high on one test but is lessening. The copper would be from bearings. I would try change intervals of 4-5k instead and recheck.
Good observation about the time-related component for copper pickup in oil, I hadn't considered that. It does seem to fit my most recent results. Also explains BlueSubie's general observation that shorter vs. longer OCIs don't seem to affect how long in total miles it takes for break-in related Cu washout to fully complete. Results of next UOA will be interesting.Copper leaches from the oil cooler, probably through a corrosion process. To a certain extent it probably happens even when the engine isn't running, but faster in warmer weather, and much faster when the engine is running. Assuming copper corrosion increases with time, temperature, and mileage, these results seem pretty reasonable.
1.5 months: 15 ppm Cu
6 months, over winter: 35 ppm
7 months, summer to winter, with 50% more miles on OCI: 57 ppm
If you had 20+ ppm copper from bearings, I think you'd see more of other metals like lead, tin, and aluminum. Lead is a touch high at 3 ppm on the OAI test, but 0 ppm with Blackstone. I wouldn't worry about it.