I have a komatsu sk820-5n and went to change my hydraulic oil and filter. I stopped by my local dealer and asked for the oil they recommended and a new filter. They gave me standard iso aw46 hydraulic oil and I went on my way and changed the fluid. My book said that komatsu recommended SAE 10w oil with a cd classification. I questioned the dealer but they said that "this is what we use". Since then I have looked another komatsu dealer's website and they had a bulletin from komatsu recommending against iso aw46 hydraulic oil as it can cause premature pump failure. I called my local oil supplier and gave him the info and he called his supplier/engineer and their books call for Chevron/Delo DRIVE TRAIN FLUID HD SAE 10W 226607. Anyone have any insight on what I should run?
I just needed to change mine as well in a Bobcat T200. I grabbed the ISO 46 off the shelf at Tractor Supply because I wasn't buing Bobcat Hydraulic Oil (All the suggest). As soon as I opened it up and noticed how thin and watery it was i took it back. I ended up putting standard tractor hydraulic/trans oil in my machine. Some will tell you to use that, some will tell you to use other stuff.
Because there is usually so much discrepancy between dealers and manufacturers recommendations, I feel safer by going with what a reputable lubrication engineer recommends (scroll down). http://www.chevronlubricants.com/products/cooling-system-fluids.aspx
Most of the major oil companies have the Datateck facility on their websites. If you search through, you will find that Valvoline recomend a 10W oil for your machine. http://www.datateck.com.au/lube/valv_auMS/default.asp RnR.