Fluid choice for a backhoe

[zkurtb]

I posted this in the Attachments forum, then noticed this category so thought I'd ask this forum as well.

I just picked up a used Woods 7500 backhoe. It has it's own tank and PTO pump, does not use the tractor fluids. As with all used items, I like to change the fluids along with checking the bolt torque, greasing, and so on.

For the fluids, the manual says there are several different recommended oil types:
SAE Hydraulic Transmission Fluid.................All Temperatures
Type "A" or "F" ATF..................................All Temperatures
SAE 30-30W...........................................90de g F and above
SAE 20-20W...........................................35-90deg F
SAE 10-10W...........................................35de g F and below

Hydraulic based fluids -- either the SAE or one of the ATFs seems to make sense for use in a Hydraulic system, rather than motor oil.

What is the difference, if any between the SAE, the ATF-A, and the ATF-F Hyd fluids, especially for an application like this?
How would those compare to motor oil?
Why use motor oil instead of a hydraulic fluid?
Does it matter?

Kurt