Great car! Thanks for the write up. I'd run an xW-40 grade and get a UOA at 5,000 miles. I ran a Mazdaspeed 3 for 158,000 miles and was told repeatedly that I would ruin the engine with a long OCI. I ended up running M1 5W-30 for 7,500 miles and the UOAs indicated a 10,000 mile OCI was plausible. That said, I would definitely see what a few UOAs indicate if I planned to run the oil past 5,000 miles.