API SN+ addresses lots of issues that came to light long after bmw mandated LL04
Whether it’s Castrol or a n other SN+ or SP are the best spec oils for modern engines
They’ve probably tackled the normal problem that most aftermarket speakers need more drive than the stock amp can deliver with more efficient speakers
The US based suppliers normally assume you’ve got a 676/677 system not the basement version
Typical injector failing open symptoms
Needs replacing ASAP if it is
Symptoms don’t accord with LPFP or HPFP normal failure
Could be HPFP seal failure in which case fuel in oil would be present