The only dino oil this car has ever seen (151,500 miles) is the original factory fill and the dino used for the AutoRX treatment and rinse cycles. The current Delvac 1 in the car now was placed in service after the AutoRX rinse cycle.
Sequence of events: D1, then M1 0w-40, then dyno for AutoRX, dino for rinse, and now D1 for just over 6k miles. BTW, I'm on my second oil filter with the D1 (just in case!). First filter was oversized Pure One PL30001, now an FL1A.
IMHO, the FL1A flows better than the Pure One equivalent. I would occassionally get start up noise with it (even when filter was brand new). NONE with the FL1A.
I'll be switching to the WIX filters I bought on sale last week at NAPA for ..... $3.95 each!!!
Should I still stick to your 7500 mile recommendation? I'm not much for doing a UOA; synthetic oil is too cheap (relatively speaking, when bought on sale and in bulk) to justify doing it.