This is for my dad's Subaru XV Crosstrek. He uses it for a short (~8 mile) commute, but it also sees longer highway trips every few weeks. He has the oil changed and all services done at the dealer for their records, though now that it's out of warranty that may change. Factory OCI is 7500 miles or 6 months, and we wanted to see if we could stretch that to one year. Looks like we can just make it. I don't know for sure what TBN the Subaru synthetic oil starts with, though I saw a VOA from 2012 that showed a TBN of 8.6. Iron is likely from the number of cold starts and shorter trips, especially in the winter. The car does not get driven very hard at all.
Next sample will likely be in one year and another 5k ish miles. What are your thoughts?
Next sample will likely be in one year and another 5k ish miles. What are your thoughts?