I'm a newbie here and am really enjoying this thread. I've a 42 yr old Troy Bilt roto tiller with a 5hp Briggs and Stratton, a Honda snowblower, honda pressure washer, honda chipper/shredder, honda generator, and a Gravely (Kawasaki 23hp) zero turn mower. All these years I've put standard conventional oil in them per owners manuals, but have gotten tired of not only keeping the variety of straight weight oils on my shelves, but trying to find what I need at the auto parts stores. I've used Mobil 1 synthetic in my cars and trucks for the last 20 years or so and never had to add oil between changes (5-7Kmiles). I'm taking the quantum leap here and going with Mobil 1 10w-30 in all my small engines after reading this along with about a dozen other online articles about synthetics in older, newer, colder, and hotter engines; and no one has said Mobil 1 synthetic is bad for them. Yes, even the 42 yr old tiller manual says I can use synthetic in the B&S!. So, I generally buy my Mobil 1 at Costco for $34 a six qt pack on coupon special, or at Wal Mart if they have it. Auto parts stores and even Amazon are much more expensive. And, Costco has free shipping if it's not in the store and you buy it online.