What oil to use in the gearbox hydraulic unit for 454 international tractor?

For the gearbox hydraulic unit of a 454 International tractor, it is recommended to use a high-quality hydraulic oil that meets the ISO 46 specification. Common options include hydraulic oils such as AW 46 or equivalent. Always refer to the owner's manual for specific recommendations, as it may specify particular brands or formulations suitable for optimal performance.