Well Today the day before my car goes into the shop for HG repair, it develops a knock right at 2500rpm not very loud but you can hear it. am sure it's rod knock my oil is clean changed 300 miles ago castrol syntech 10/40 with lucus, how did this happen with i know my motor has over 167000 miles on it but still man it sux bad. so i guess now i need a motor.