I have a 2015 Craftsman Push Mower with a Briggs and Stratton model 10000 725exi series OHV engine. They claim that the original oil is good for the life of the engine and does not require changing. However, I don't believe that and so I still want to change the oil before each mowing season anyway. The owner's manual says to use a detergent oil classified for service SF, SG, SH, SJ, or higher. SAE 30 is recommended for use in temperatures above 40 degrees F, which is what I plan to use (I live in Florida). When I was browsing the oil selection at Walmart, I noticed that for the SuperTech brand SAE 30 viscocity, there was a choice of "Lawn Mower Oil" and "Heavy Duty 30". According to the labels, the lawn mower oil meets the SJ service level that does satisfy my engine requirements, but the HD 30 meets the SN spec, which I know is a more modern spec. and currently the highest industry standard for oil available. Ultimately, I am tossed up between the two as to which would be the better choice for my application. So my question here would be what is the actual difference between these two oils in terms of formulation and intended application and which of the two seems like a better choice for my mower?