Engine tapping noise 2001 s40
 

My engine started making a tapping noise when I start it up especially cold, then it goes away. I have 177,000 kms and although I bought it second hand AT 99,000 KMS, I have taken very good care of the car and changed the oil (syn) and filter around every 7000 kms. Could this noise be coming from the lifters? Is it something that one day just starts happening, no warning? Is it very serious? What can I do about it? Should I add a engine supplement or stay away from that?




Thank you!