46 or 68

[panamaguy]

Hi. Need so impute on hydraulic oil. I have a mini excavator and the manual calls for number 46 hyd oil. I live in Panama and everyone seems to use number 68. . What is the difference in these and could they be interchangeable. My thoughts and not sure if this is correct but seeing the machine is sold in THE USA could the call for 46 be because of the temperature up there and 68 used here because a cold night is 72 degrees? Any oil experts have the answer.