I have Honda GP5 (75000km) and all service done by Sterling. They have used Havoline 0-20w fully synthetic oil changed by 5000km. From this forum i have learned fully synthetic oil can run 10,000km and asked them about why they recommend 5000km for fully synthetic oil. Their answer was if i use Mobil ( which cost double compared Havoline ) i can run 10,000km but for Havoline it's 5000km. Is there any truth to this ? Also i would like to know what's agent recommended oil and oil change interval ( i never gone to agent ) . Also since daily running on heavy traffic route ( 45min to go 12km normally ) i'm fear waiting for 10,000km. Is my fear baseless ? ( i'm asking this since i hope to keep car around 200,000km and want to do best maintenance today so i can save bit money in future )