Brent, I have been doing some research on John Deere Hy-Gard low Viscosity Transmisson_Hydraulic Oil because it is the most convenient one for me to get. I have communicated with John Deere and Denison. I got some specs from John Deere which I reviewed with Denison and was told that it was very similar to Dextron and whould be acceptable as long as it is low in Zinc. I contacted Imperial Oil, Toronto, Onatario because they supply the Hy-Gard. Without revealing and John Deere trade secrets, I was told that this type of oil usually has Zinc in the additive package to reduce wear. Denison said the zinc will attack brass parts in the Denison transmission. I was told that the Denison model hydrostat in the combines is a close tolerance hydrostat. Maybe, the Dynapower and the Sunstrand are not and don't have brass parts. I will post any more information I get. I have not checked the oil that is used in the Case_IH combines or any other brands. Was hoping someone else has. Thanks for your response. John