Hi guys, Just wondering if someone can offer some opinions. Changed the oil last Sunday, car is quite old - am using a 15W-40 oil. Also added the Nulon additive for "stop smoke". Started to notice a loud knock when the engine starts. Just one knock only at start-up. If the car has been sitting for more than an hour or so, then this happens. Just looking to see if anyone has any insights into this. Quite an old car, done just over 300,000 kms. Someone suggested that it might be the oil pump, as its using a thicker oil - this causes problems in winter. Thanks guys, appreciated.
