I'm wondering if my mother's brand new 2005 Toyota Camry with the 2AZ-FE engine will benefit from GC? Her oil change is coming up soon...right now she has the Castrol GT-X 5w-30 with a fram filter...mileage is at 5,500...should I switch her up to GC @ 6,000 miles? Whats a good oil interval for GC on a 2az-fe that is primarily granny driven?