'07 Kia Sedona 3.8L uses 5W20 (oil cap recommendation).At 40K miles I switched from conventional oil to 5W20 synthetic M1 or PP and run 6K miles / 6 months OCI's . Now the engine I just noticed has 150K miles on it and it doesn't burn any oil nor does it leak . I wondered if I should switch to a HM synthetic or not ? Also as the motor is 8 years old now does it make any sense to go up to a 5W30 synthetic - or just stay the course of what I have been doing ? My only real concern is the Kia 3.8L has a timing chain and is know to beat up oil pretty good so I wonder if moving up to a HM , 5W30 or both is better at this 150K mile juncture ?