Bruce, I don't yet understand your point. It is possible that B&S has published a newer specification than the one given in the "General Information" section of their overhaul manual that I downloaded from the internet, but ordinary engine oil meets the specification in the manual I have. They say, "Any high quality detergent oil having the American Petroleum Institute classification "For service SC, SD, SE or MS" can be used in Briggs & Stratton Engines". That is the normal specification of automotive engine oil. It is worth noting that B&S prefer straight SAE 30 oil to multigrade oil, and all ordinary engine oils these days are multigrade. However B&S say multigrade is satisfactory if straight SAE 30 is not available.
The engine has no oil filter whether or not you use some 'special' oil. That is why B&S require that you change the oil every 25 hours, and more often under dirty operating conditions. Cars used to have to have their oil changed every 1,000 miles before they had oil filters, for the same reason. Also, I do not know what is different about this allegedly-special oil you recommend. Ordinary API-specification automotive oil is the most advanced oil formulation I know of, with two provisos. First, synthetic oil has slight advantages over mineral oil under extreme conditions, which are certainly not encountered in a B&S engine. Second, there are additives that can improve the performance of oil, again under extreme service conditions. For example it is a very good idea to use an oil rated for diesel engines in that kind of engine, because they are rather hard on oils. Racing engines have some really exotic oil additives, formulated for that particular engine.
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