Hitachi ZAXIS 120-6 class Operator's Manual page 358

IMPORTANT:
 When connecting hydraulic hoses and pipes, take
special care to keep seal surfaces free from dirt and
to avoid damaging them.
 Wash hoses, pipes, and the tank interior with a
washing liquid and thoroughly wipe off before
reconnecting.
 Only use O-rings that are free of damage or defects.
Be careful not to damage them during reassembly.
Do not allow high pressure hoses to twist when
connecting them. The life of twisted hoses will be
shortened considerably.
 Do not use hydraulic oils other than those listed in
the table "Brand names of recommended hydraulic
oil".
 When adding hydraulic oil, always use the same
brand of oil; do not mix brands of oil. When using
another manufacturer's hydraulic oil, be sure to
change the full amount.
 The new machine is filled with Hitachi Genuine
Hydraulic oil 5000 (change interval: every 5000
hours). When adding or changing the hydraulic oil,
continue to use Hitachi Genuine Hydraulic oil 5000.
 Never run the engine without oil in the hydraulic oil
tank.
MAINTENANCE
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