Has anyone found a replacement oil for the g2 hydro fluid? Mobil DTE18m doesn't have high heat quality for the diesel units. I got the specs from Grasshopper: No viscosity improvers; pour point -50 F; viscosity index 180; Needs 1400 ppm of zinc. Anyone know where to find this?? Help at $50+ a gallon someones making money. I can get DTE18m for 8.32 a gallon.