Synthetic & Multigrade Hydro Fluid

[Anonymous Poster]

Has anyone had any success in using either a synthetic or multigrade hydro fluid in reducing the whine noise made by hydrostatic transmissions in cold weather? If you have, I'd appreciate knowing what your experience was and how much of a difference it seemed to make. I have a relatively new NH TC40D and there is a fair amount of noise from the transmission until it warms up, so I'm thinking of switching at the first fluid change.