[JDPascal]

Lots of question here – lets give it a try.

First, if the “cleaning solution” was a standard engine flush, that would thin the oil out. The containers usually say not to run the engine above an idle and for only 10 or 15 minutes.

If it was something else, then I would have no idea unless you could provide a brand name and maybe look at the instructions on the bottle.

If the knock is from the top of the engine, then you are likely hearing noise from the valve train. That could be the lifters, camshaft, rockerarms, pushrods or even a worn tip on the valve stem. Being as it started after the oil was doctored, I would suspect a sticky lifter but who knows what you would find when you get in there.

You can confirm the noise source and identify the valve location by removing the valve cover and running the engine at an idle. If you have a mechanics stethescope great otherwise push down on the moving rocker arms one at a time and listen for a change in the sound. Or you could roll up a sheet of paper into a cone and listen with the large end at your ear to each rocker arm at the push rod or valve ends.

The oil in the air filter is likely the result of the hose to the PCV valve being restricted. Pressure builds in the crankcase and pushes the oil into what should be the in take for the PCV. Replace or clean the hose and the PCV filter and replace the PCV valve.

Unless the engine is running poorly, has high oil consumption or a proven low oil pressure problem, I would just look into the upper engine noise for now and keep an eye on the performance and oil pressure.

I think I’ve addressed all the concerns you raised.

Hope this has helped.

JD