Recently came into possession of a Cockshutt 1655 diesel tractor in very good condition. I’m more of an operator than a mechanic, thiugh I do have basic skills. Was wanting to change out all the fluids. Anyone have a recommendation on hydraulic fluid and engine oil? Tractor is 50 years old and fluids and oils have changed a lot in that time. Looking for what works best. Owners manual calls for oliver specific hydraulic fluid and for engine oil simply says 30. Are new oils better, or synthetics?