They don't have a preferred brand. From the chart on page 50-9 of the Operators Manual it appears the oil grade VG 32 is best suited for when the tractor would be used in below freezing weather, such as snow pushing and under 80 degrees. The VG 56 would be best suited for warmer climates where the tractor isn't used in below freezing temps. Personally I've used the Traveller brand from Tractor Supply because it was readily available near me. They sell it in a 5 gallon pail and a 2 gallon jug. Get one of each and you have enough for the 6.6 gallon hydraulic fluid change.