I didn't find them useless, I found them interesting. Certainly nothing worth getting overly excited about. Is it entirely relevent to today's vehicle? No, and I didn't claim it was. However, if you look at todays vehicles they have good air filters, good oil filters, chrome rings, and they last a long time. At least mine do but that is a small sample size.
I think that the testing was reasonable. Varying sizes of particulates were introduced into what appeared to be a dust tunnel. This is a controlled environment; something not found in the 'real world'. Several types of air filters (and lack thereof) as well as an oil filters were tested. Engine wear areas were measured (ring gap, cylinder bore, bearing weight, bearig clearance, etc). At the VERY least, it seems like a good first step for what would have probably been early industry testing.
I haven't done an exhaustive search of any one topic since I finished my thesis. There were only one or two in about a hundred with conflicting conclusions. That doesn't invalidate their work and it doesn't make it anecdotal. More likely, it wasn't fully understood (and maybe still isn't). However, each paper still adds to the body of knowledge. Pouring over all of those papers allowed me to see things that the individual authors did not. Progress is made in small, incremental steps, building off of prior work.
