Well, normally when it is lifters it is one or two lifters and you can pick it out because it happens every 2 rotations, if you understand how I mean. But this is either like every rod bearing is worn out equally, or every valve is adjusted to way to big clearance because it is not one knock or ding ding that is standing out from the rest. That was what puzzled me, and it sounds like it comes from the lower part of the engine when I stay at the left fender and have the entire side of the engine towards me. But, I have bought a valve cover gasket today, and will look into the valve issue, and I have ordered 20W-50 mineral oil and got an oil filter.
If this is an occasion where all the valves are equally totally out of adjustment, then either someone must have had the wrong value, or it has been driven and driven without any lifter adjustment for a very very long time.
