I run a farm operation in Northern IL, and find that the John Deere Universal Hyd. Tractor Fluid that we run in our loader tractor hydraulics (per recommendation) gets viscous enough in cold weather to necessitate long warmup times in order to get the loader to work to capacity, and the power steering, which shares common fluid, to turn without herculean effort. Are there fluids more suited to this application, or an additive that would effectively improve cold weather functionality?