The 5 hour oil change is from times past, much like changing your new truck's oil when you hit 500 miles. Neither Kohler nor B&S recommend it, but old habits die hard. Do not use straight 30 weight oil, it can cause problems with the hydraulic lifters in the Kohler engines. I don't know about the B&S model.
I've used Mobil 1 5w-30 since my first oil change at 25 hours. I've been running Mobil 1 for more than 100 hours now without any problem or loss of oil. I've change it every 25 hours, and its always come out very clean so I think like with cars its safe to leave sythetic in for two to four times as long as dino oils. I just don't want to use my tractor to test that theory.
I've used Mobil 1 5w-30 since my first oil change at 25 hours. I've been running Mobil 1 for more than 100 hours now without any problem or loss of oil. I've change it every 25 hours, and its always come out very clean so I think like with cars its safe to leave sythetic in for two to four times as long as dino oils. I just don't want to use my tractor to test that theory.