Your power steering system is NOT like an automotive system. Your tractor's power steering is a hydraulic system just like the main hydraulic system and uses NH134. To tell you the truth, I'd suck a pint out of the hydraulic reservoir before I'd use standard PS fluid. You just don't know the lube properties of ATF and some chemical additives may harm the seals in your power steering hydraulic cylinder and pump. The beauty of our tractors is you only need engine oil, hydraulic oil, and grease to meet all the lubrication needs. Heck, the next time you change hydraulic fluid, keep a little for the power steering and the front differential. The main hydraulic reservoir has to be cleaner because of the critical tolerances of the HST. I'd have no qualms about saving 300 hour fluid to use in the PS and front differential, but I'd never use a different fluid like ATF. Heck, I'd even put 10w30 motor oil in before ATF.:2cents:
