I recently purchased a 2011 Cub Cadet Tank M72 and want to change all fluids including the Hydrostatic Fluid. The manual calls for Rimula 15W40 which I have been told Rotella has replaced this. However it also sys add 1.5 ounces of Ornite Additive. I do not know what this is or what it does. Does anyone know where to get this and is it that important? Thanks