I just purchased a new ariens pro32 snowblower. It has a briggs and stratton snow series (alumium sleeve version) 16.5ft/lb engine. The instructions said to change the oil after the first 2 hours and every 25 hours thereafter. The dealer ran it for a 20 minutes before delivering it to me to "make shure everything was ok". After I received it I warmed it up and used it for about an 45 minutes then changed the oil. There were a good amount of metalic glitter clearly visible although too small to feel. After that I installed an hour meter and have a about 10 hours total. I have changed the oil 10 times with about an hour between changes. It still looks about the same. For the first 7 hours I used mineral oil then switched to synthetic, both 5w30. From what I read this is common upon break-in on engines without an oil filter, but after 10 hours. B&S customer service is not open until after the new year.