RepairPal Certified shops can diagnose and repair your 1997 BMW 328i. They provide transparent pricing with a minimum 12-month or 12,000-mile warranty on repairs and services.
Synthetic is best, but is not required on your model.
Your motor oil could range from 5-30 to 10-40. In San Diego, either is fine, but many people swear by 10-40 synthetic.