I owned a new '05 WRX and ran Mobil1 5w30 from 8,000 miles on.
Changed every 4k miles.
Started to burn half quart between changes around 110k miles.
Spun a rod bearing, while bombing some back roads, after 10 years and 159k miles of a heavy right footedness.
Stock Turbo, CBE, slight tune, nothing crazy.