I'd love some advice guys. Straight SAE 30 oil seems to be recommended for most mower engines unless using synthetic. I can buy Valvoline SAE30 or Pennzoil SAE30 for about half the price of Briggs SAE30. Also, the "auto" oil meets higher modern standards. The "mower" oil says it is made especially for small 4 strokes, but it seems they're just trying to sell a more expensive oil. My assumption is that the "auto" oil is both better and cheaper. Am I wrong? My mowing is in warm conditions (mostly 70-100 F) under light to medium workloads (weekly residential-no brush or field mowing) I'd appreciate ANY input in this area.