Yes, it's fun to debate, but nobody's likely to change any long-held beliefs. The clearances on a stovebolt engine are so big in comparison to modern engines that they can survive without a filter at all. What we used to consider to be "normal" clearance is "worn out" on today's production engines. Hypereutectic pistons are supposed to be able to run with .0005" skirt clearance because they have virtually no thermal expansion at normal running temperatures. Ditto on rod and main bearings- - - -the clearances are so close they have to have the zero or 5 weight oils just so some lubricant can get between the parts. 30 weight just won't fit into those spaces well enough to prevent galling. OTOH, the super-lightweight oil flows away from stovebolt parts almost instantly because of the wide gaps between them. My biased opinion- - - -your mileage may vary!
Jerry
