Marine Steering Hose, 0.31 Inch ID, Up To 1000.00 PSI

The 212°F ceiling is the overall temperature rating for the hose when running standard petroleum-based hydraulic fluid. That 135°F limit only kicks in if you're running synthetic hydraulic fluids or water-based fluids instead. Those fluid types are harder on the inner tube material, so the safe operating temperature drops. Stick with conventional hydraulic fluid and you've got the full range. Switch to synthetics or water-glycol blends and you'll want to keep temps under 135°F to avoid degrading the core tube over time.