A neighbor gave me several 16 oz cans of Evinrude oil for 2-cycle engines. It is for a 50:1 mix. The cans are old enough to have no UPC bar code and open with pull tabs. My question: does unopened oil deteriorate in the container and is there any reason not to use this oil in my air cooled 2-cycle engines (chain saws, weed trimmer, tiller)? Thanks