Hydraulic oils or Hydraulic fluids are fluids that are non-compressible that are used in all kinds of hydraulic machinery or equipment including cranes, diggers, drill floor power units and hydraulic ring mains. They can by synthetic or mineral based and are used in the transfer of power but can also be used as a sealant, coolant or lubricant in machinery or equipment.
Find out the difference between synthetic and mineral based oils here
Comment: The UK is closer to deindustrialisation than reindustrialisation
"..have been years in the making" and are embedded in the actors - thus making it difficult for UK industry to move on and develop and apply...