About to purchase a used S-250 with approx 1350 hours. Problem: the oil in the hydro sight glass has a beige, milky look to it. Is this an indication of water in the fluid. If so, is this a "walk away from deal" no matter how good it appears? What would likely be the corrective action.....change the oil and run then drain and replace again? Machine runs very well with no noticeable problem with lift or blade action. Pulls well with no jumping and etc. Any comments would be greatly appreciated!