I have a lawn mower with a Briggs 12.5 HP single cylinder engine. The mower calls of SAE 30 weight oil, but I use this mower alot in the snow and cold temps and I am wondering if a strait 30 weight is too thick on starts ups. could I use something like rotella t6 5w-40 or t5 10w-30? also, i have a bunch of Honda GN-4 10w-40 motorcycle oil around since I get it for free alot from my work. Can I use this? Im kinda looking for something I can change annually, i don't use the mower a whole lot, maybe once a week for 2-3 hours all year. maybe a little less in winter.