Yes, speedpup, hot oil is a machine killer. Over time, hot oil will turn o-ring seals and hoses hard as a rock. With that said, many of the older telehandlers didn't really need a cooler on the hyd system because many had very large reservoir tanks to dissapate the heat before it returned to the working system. Newer machine designs have compacted machines and components somewhat. Likewise, hyd tanks have gotten slightly smaller. Now hyd coolers have become necessary on the hyd systems of these machines. As for your machines, regardless of model, if they are running fairly cool on hyd oil, not really necessary to add cooler, cold hyd oil is no better for components operations than hot oil being hard on seals. Generally speaking, operate one of your machines for a couple hours and carefully place your hand on the hyd tank. If the tank is just warm, your good. But, if you can only leave your hand there a couple of seconds until it becomes uncomfortable, you should consider installing an oil cooler. Hope this helps ya.