Im sorry but I am not going to change the oil every week like some guys "claim" they do. If I did everything that a person is supposed to do I would never have any time for myself or my family. Would it blow your mind to know we change our oil 3 times a year and in over 20 years have never had an engine failure due to oil problems? Not only that but it costs us less money and less time to do it this way.I find synthetic a waste. I change my oil twice as often as recommend and filter 4 times more often then recommend and I would never think about doing it with synthetic. I'm sure synthetic is better oil but more frequent changes seem to do the trick for us.
There is a large difference between 5w-30 and 30 weight oil! If your book calls for 30wt. for hot weather, then I'd just stick with that, and no, there's no 30wt in synthetic that Iv'e ran across. Most newer engines, Kohler and Briggs take 10w-30. Kawisaki I'm not sure about.Does Mobil 1 make a sraight 30 weight? Is there any harm in running say a 5w-30 or 5w-20 oil. I totally agree with synthetic oils being the way to go. These types of engines only require around 2 quarts, so that only a few dollars extra to protect a 7-12k machine.