I haven't measured the temperature of the hydro oil, Jim. So far, I've only used one implement at a time, either the deck or the 54" blade. Seeing that these haven't put a big strain on the hydro, the oil cooler or syn oil might be okay only if we lived down in Arizona or New Mexico. I'm a little anal retentive with my bikes and cars, so being no different with this newly acquired tractor, I've gotta ask Kent Ortman this question. I've got one of those Hayden oil coolers laying around. Could it be plumbed into the long suction tube that you mentioned? If you're running multiple hydraulic implements, this probably can hurt and would increase capacity at the same time.
Cheers,
Stephen