i am also familiar with the various opinions on engine oil types here in switzerland. some say this oil is the best, others say this is the best. I've been using the 20 / W50 in all of my oldtimers for decades. I have vehicles from the 40s, 50s and 60s. In my shop, my boss also has vehicles from the 20s and 30s. I use SAE 30 for these old cars without oil filters. As I said, I've been using these 2 oils for several decades and have no problems with them. a good friend with his own garage and several customers with oldtimers, he has been using the 20 / W50 for several decades for all his cars and those of his customers and has no problems with it.
With the engine of my Impala it is correct, as some of you have said, that the engine has warped due to a lack of oil due to the clogged oil pump strainer and the cooling water in the oil / engine. When disassembling the engine, I also noticed that it was rusty inside in many places. He's probably stood there for a long time with moisture in the engine.
since i am rebuilding the engine from scratch, it will work properly after correct assembly. what is not yet entirely clear to me is the break-in of the engine. you in America do it differently than we do here in Switzerland. we first let a new engine warm up for half an hour at idle speed. Afterwards we change the oil and tighten the screws on the cylinder head. after driving 300 miles at moderate speeds, we change the oil again. after another 300 miles of leisurely driving, only then do we really load the engine. you do that, I think differently, what I read here in the forum