Originally Posted by LantanaTX
I have always been taught that oil is like little ball bearings and that the weight of the oil needs to conform to the tolerences in the bearings, rings and piston to cylinder clearances. As an engine wears these tolerences increase it is a good idea to increase the weight of the oil to properly fill these clearances. I personally don't like sludge and blown engines and therefore use high quality synthetics. His comment on how to find the source of the knock was a good one and a technique my grandfather taught me 35 years ago. He should be looking for the source of the knock before throwing parts and dollars at it.
My point was that from my experience as well as a local person last year with a N/A both had the same issue which was a loud know that pasted for about 5 seconds right after start up as well as a constant but softer tap during idle. They were gone once the correct oil was used. I am in no way suggesting this will replace a mechanical issue but he needs an oil change and already mentioned it has the incorrect weight in it. It is worth a try before spending $ with a mechanic as it needs done anyway.
I have been involved with cars for over 30 years and even though I may not attempt some of the projects that a few on here including yourself are working on, there are some things that don't need a whole lot of explaining and when I see a comment like oil is oil, what the heck!!!
