I've used Quaker State non synthetic at 20:1 since day one (Kings 80cc). Yeah the old MotoSchwinn throws a bit of oil on my tennis shoes when I'm riding, but so what. And the next morning there is a nickel size spot on it's pad.... In the 80's we had a 1969 Austin Mini Cooper S, we viewed the oil spot it left not as a leak, but a visual reference that it in fact had oil in it. That's the same agreement the Old Schwinn and I have.