I've owned this 1980 928 for a couple of years now and its had noisey lifters since day one. I assumed it would go away after being driven for a while as it wasn't used much by previous owner, so I tried lifter ease in the oil with minimal success on rare occasions it would quiet down but not for long. It's due for an oil change soon (castrol gtx3) and was wondering about putting in some oil flushing additive before I change oil and filter any advice welcome. Oil pressure is good but the noisey motor is a pain and I would like to get rid of it. Thanks Dobbo.