Can I use oil labeled as cool for 1 to 40 mix, in a 1 to 50 mix engine. I have all this Shindaiwa oil that says good for 1 to 40 in Shindaiwa engines. My echo trimmer and blower say use oil at 1 to 50. Can I use the same oil? At 1 to 50? Can I use it at 1 to 40, even tho the kioritz engine in the echo says 1 to 50 is all you None of the oil has any labeling with specs on it, such as the echo manual says "ISO-L-EGD (ISO/CD13738) and J.A.S.O. FC Standards". No oil has this spec labelled on it, that I've ever seen. My 1 to 100 oil which says NMMA-BIA approved. The echo manual doesn't say avoid outboard motor 2-cycle oil, like my Weed Eater Poulan manual says. I don't know why I can't use this outboard motor oil. It probably just has extra additives to help avoid salt-water corrosion of aluminum and iron-steel engine parts. Or is just about any 2-cycle oil fine?